typedef struct __CFRunLoopMode *CFRunLoopModeRef;
struct __CFRunLoopMode {
    pthread_mutex_t _lock;          互斥锁,来使多个线程保持同步
    CFStringRef _name;              运行在那个model下，例如 @"kCFRunLoopDefaultMode"
    CFMutableSetRef _sources0;      触摸事件，PerformSelectors，非基于Port的
    CFMutableSetRef _sources1;      基于Port的线程间通信，基于Port的
    CFMutableArrayRef _observers;   添加监听的方法:
    CFMutableArrayRef _timers;      定时执行的定时器
    CFMutableDictionaryRef _portToV1SourceMap;
    __CFPortSet _portSet;
    ...
}

    CFRunLoopObserverRef这是一个观察者，主要用途就是监听RunLoop的状态变化
    /* Run Loop Observer Activities */
    typedef CF_OPTIONS(CFOptionFlags, CFRunLoopActivity) {
        kCFRunLoopEntry = (1UL << 0),                即将进入RunLoop
        kCFRunLoopBeforeTimers = (1UL << 1),         即将处理Timers
        kCFRunLoopBeforeSources = (1UL << 2),        即将处理Sources
        kCFRunLoopBeforeWaiting = (1UL << 5),        即将进入休眠
        kCFRunLoopAfterWaiting = (1UL << 6),         刚从休眠中唤醒
        kCFRunLoopExit = (1UL << 7),                 即将退出RunLoop
        kCFRunLoopAllActivities = 0x0FFFFFFFU
    };

@class NSTimer, NSPort, NSArray<ObjectType>, NSString;
FOUNDATION_EXPORT NSRunLoopMode const NSDefaultRunLoopMode;
FOUNDATION_EXPORT NSRunLoopMode const NSRunLoopCommonModes;
 
@interface NSRunLoop : NSObject {
    //获取当前RunLoop对象
    @property (class, readonly, strong) NSRunLoop *currentRunLoop;  
    //获取主线程的RunLoop对象
    @property (class, readonly, strong) NSRunLoop *mainRunLoop;     
    //获取当前RunLoop的运行模式
    @property (nullable, readonly, copy) NSRunLoopMode currentMode; 
    添加一个定时器到runloop循环中，并指定运行模式
    - (void)addTimer:(NSTimer *)timer forMode:(NSRunLoopMode)mode;
    添加一个端口到runloop循环中，并指定运行模式
    - (void)addPort:(NSPort *)aPort forMode:(NSRunLoopMode)mode;
    从runloop循环中移除一个端口到，并指定运行模式
    - (void)removePort:(NSPort *)aPort forMode:(NSRunLoopMode)mode;

    - (nullable NSDate *)limitDateForMode:(NSRunLoopMode)mode;
    - (void)acceptInputForMode:(NSRunLoopMode)mode beforeDate:(NSDate *)limitDate;
@end

@interface NSRunLoop (NSRunLoopConveniences)
    进入处理runloop的事件循环
    - (void)run;
    等待多长时间进入处理runloop的事件循环
    - (void)runUntilDate:(NSDate *)limitDate;
    - (BOOL)runMode:(NSRunLoopMode)mode beforeDate:(NSDate *)limitDate;
    ios(10.0)
    - (void)performInModes:(NSArray<NSRunLoopMode> *)modes block:(void (^)(void))block;
    ios(10.0)
    - (void)performBlock:(void (^)(void))block;
@end

    Delayed perform
@interface NSObject (NSDelayedPerforming)
    - (void)performSelector:(SEL)aSelector withObject:(nullable id)anArgument   
    afterDelay:(NSTimeInterval)delay inModes:(NSArray<NSRunLoopMode> *)modes;
    
    - (void)performSelector:(SEL)aSelector withObject:(nullable id)anArgument  
    afterDelay:(NSTimeInterval)delay;
    
    + (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget selector:(SEL)aSelector  
    object:(nullable id)anArgument;
    
    + (void)cancelPreviousPerformRequestsWithTarget:(id)aTarget;
@end

@interface NSRunLoop (NSOrderedPerform)
    - (void)performSelector:(SEL)aSelector target:(id)target argument:(nullable id)arg  
    order:(NSUInteger)order modes:(NSArray<NSRunLoopMode> *)modes;
    
    - (void)cancelPerformSelector:(SEL)aSelector target:(id)target argument:(nullable id)arg;
    - (void)cancelPerformSelectorsWithTarget:(id)target;
@end

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor redColor];
    //1. 创建timer
    NSTimer *timer=[NSTimer timerWithTimeInterval:2.0 target:self selector:@selector(timerChange)  
    userInfo:nil repeats:YES];
    //2. 将timer添加到当前RunLoop(主线程)中, 如果不添加到NSRunLoop中,NSTimer是无法工作的
    [[NSRunLoop currentRunLoop] addTimer:timer forMode: NSDefaultRunLoopMode];
    
    // 3.添加到UITrackingRunLoopMode运行模式下  NSTimer无效
    //[[NSRunLoop currentRunLoop] addTimer:timer forMode:UITrackingRunLoopMode];
    // 4. 添加到NSRunLoopCommonModes运行模式下  NSTimer有效
    //[[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
}

-(void)timerChange {
    NSLog(@"timer来了");
}

@interface WGRunLoopVC ()
@property(nonatomic, strong) dispatch_source_t timer;
@end

@implementation WGRunLoopVC

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor redColor];
    
    self.timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, 
    dispatch_get_global_queue(0, 0));
    //设置定时器各种属性  参数: 定时器 开始时间 时间间隔
    dispatch_source_set_timer(self.timer, DISPATCH_TIME_NOW, 1.0 * NSEC_PER_SEC , 0);
    // 设置Timer的回调
    dispatch_source_set_event_handler(self.timer, ^{
        NSLog(@"当前的线程:%@",[NSThread currentThread]);
    });
    //启动Timer
    dispatch_resume(self.timer);
    
}

-(void)timerChange{
    NSLog(@"timer来了");
}

打印结果:  当前的线程:<NSThread: 0x60000180fe00>{number = 4, name = (null)}
         当前的线程:<NSThread: 0x60000180fe00>{number = 4, name = (null)}
         当前的线程:<NSThread: 0x60000180fe00>{number = 4, name = (null)}
         ...

//WGRunLoopVC.m文件
@interface WGRunLoopVC ()
@property(nonatomic, strong) NSTimer *timer;
@property(nonatomic, strong) NSString *name;
@end

@implementation WGRunLoopVC

- (void)viewDidLoad {
    [super viewDidLoad];
    self.name = @"zhang san";
    self.view.backgroundColor = [UIColor redColor];
    //1. 创建NSTimer 2.自动添加到RunLoop中 3.会导致循环引用问题
    //scheduledTimerWithTimeInterval方式默认已经添加到RunLoop中了
    self.timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self  
    selector:@selector(timerChange) userInfo:nil repeats:YES];
}

-(void)timerChange{
    NSLog(@"timer来了,名字是: %@", self.name);
}

-(void)dealloc {
    NSLog(@"WGRunLoopVC页面销毁了");
}

// 这里我们以touchesBegan/viewWillDisappear为例来 模拟合适时机
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self.timer invalidate];
    self.timer = nil;
}

-(void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [self.timer invalidate];
    self.timer = nil;
}

__weak typeof(self) weakSelf = self;
self.timer=[NSTimer scheduledTimerWithTimeInterval:0.1 repeats:YES block:^(NSTimer * _Nonnull timer){
    NSLog(@"timer来了,名字是: %@", weakSelf.name);
}];

// 这里我们以touchesBegan/viewWillDisappear为例来 模拟合适时机
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self.timer invalidate];
    self.timer = nil;
}

-(void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    [self.timer invalidate];
    self.timer = nil;
}

//利用RunTimer添加方法需要导入头文件
#import <objc/message.h>

@interface WGRunLoopVC ()
@property(nonatomic, strong) NSTimer *timer;
@property(nonatomic, strong) id target;
@property(nonatomic, strong) NSString *name;
@end

@implementation WGRunLoopVC

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor redColor];
    self.name = @"zhang san";
    //1. 初始化中间者
    _target = [[NSObject alloc]init];
    //此时的_target并不具备处理消息(timerChange)的能力,所以我们需要通过RunTime为_target添加处理消息的能力
    /*
     给当前的类[NSObject class]添加方法
     添加方法编号: 其实就是方法名称
     添加方法的IMP地址: 因为_target对象内部没有timerChange方法,所以这里的方法地址用的就是当前对象  
     self中的方法timerChange地址,然后把这个地址交给_target对象
     */
    class_addMethod([NSObject class], 
                    @selector(timerChange),   
                    class_getMethodImplementation([self class], 
                    @selector(timerChange)), 
                    "v@:");
    // 如果只添加方法是不行的,因为定时器任务中有打印self.name,但是_target对象底层是结构体,它的内部并  
    没有name这个属性,所以程序运行会crash,那么我们就需要再动态添加_target对象的name属性
    //class_addIvar([NSObject class], [@"name" UTF8String], sizeof(id), log2(sizeof(id)), "@");
    self.timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:_target  
    selector:@selector(timerChange) userInfo:nil repeats:YES];
}

-(void)timerChange{
    NSLog(@"timer来了,名字是:");
}

-(void)dealloc {
    NSLog(@"WGRunLoopVC页面销毁了");
    [self.timer invalidate];
    self.timer = nil;
}

    // 自定义WGProxy类继承自NSProxy 
    //WGProxy.h文件
    /// NSProxy消息转发的基类
    @interface WGProxy : NSProxy
    @property(nonatomic, weak) id target;
    @end
    
    //WGProxy.h文件
    @implementation WGProxy
    //作用就是 消息转发
    -(void)forwardInvocation:(NSInvocation *)invocation {
        [invocation invokeWithTarget:self.target];
    }
    -(NSMethodSignature *)methodSignatureForSelector:(SEL)sel {
        return [self.target methodSignatureForSelector:sel];
    }
    @end

    // 在WGRunLoopVC文件中引入WGProxy头文件
    #import "WGProxy.h"
    //WGRunLoopVC.m文件
    @interface WGRunLoopVC ()
    @property(nonatomic, strong) NSTimer *timer;
    @property(nonatomic, strong) WGProxy *proxy;
    @property(nonatomic, strong) NSString *name;
    @end

    @implementation WGRunLoopVC
    - (void)viewDidLoad {
        [super viewDidLoad];
        self.view.backgroundColor = [UIColor redColor];
        self.name = @"zhang san";
        // 1. 实例化WGProxy,注意它只有alloc方法没有init方法
        self.proxy = [WGProxy alloc];
        // 2. 将self设置为proxy对象的target(类似代理)
        self.proxy.target = self;
        // 3. 将NSTimer的target设置为proxy对象
        self.timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self.proxy  
        selector:@selector(timerChange) userInfo:nil repeats:YES];
    }

    -(void)timerChange{
        NSLog(@"timer来了,名字是: %@", self.name);
    }

    -(void)dealloc {
        NSLog(@"WGRunLoopVC页面销毁了");
        [self.timer invalidate];
        self.timer = nil;
    }

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor redColor];
    //1. 创建子线程
    NSThread *thread = [[NSThread alloc]initWithBlock:^{
        //2. 在子线程中添加NSTimer并将其添加到NSRunLoop中
        NSTimer *timer = [NSTimer timerWithTimeInterval:2.0 target:self  
        selector:@selector(timerChange) userInfo:nil repeats:YES];
        [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
        //3. 打印当前线程
        NSLog(@"当前线程是:%@",[NSThread currentThread]);
    }];
    [thread start];
}

-(void)timerChange{
    NSLog(@"timer来了");
}
    
打印结果: 当前线程是:<NSThread: 0x600001f6a180>{number = 6, name = (null)}

// 1. 自定义继承自NSThread的类
@interface WGThread : NSThread

@end

@implementation WGThread
-(void)dealloc {
    NSLog(@"线程WGThread已经销毁了");
}
@end

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor redColor];
    //1. 创建子线程
    WGThread *thread = [[WGThread alloc]initWithBlock:^{
        //2. 在子线程中添加NSTimer并将其添加到NSRunLoop中
        NSTimer *timer = [NSTimer timerWithTimeInterval:2.0 target:self   
        selector:@selector(timerChange) userInfo:nil repeats:YES];
        
        [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
        NSLog(@"当前线程是:%@",[NSThread currentThread]);
    }];
    [thread start];
}

-(void)timerChange{
    NSLog(@"timer来了");
}

打印结果: 当前线程是:<WGThread: 0x600002dda3c0>{number = 5, name = (null)}
        线程WGThread已经销毁了

@interface WGRunLoopVC ()
@property(nonatomic, strong) WGThread *thread;
@end

@implementation WGRunLoopVC

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor redColor];
    //1. 创建子线程
    self.thread = [[WGThread alloc]initWithBlock:^{
        //2. 在子线程中添加NSTimer并将其添加到NSRunLoop中
        NSTimer *timer = [NSTimer timerWithTimeInterval:2.0 target:self  
        selector:@selector(timerChange) userInfo:nil repeats:YES];
        
        [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
        NSLog(@"当前线程是:%@",[NSThread currentThread]);
    }];
    [self.thread start];
}

-(void)timerChange{
    NSLog(@"timer来了");
}

打印结果: 当前线程是:<WGThread: 0x600002d8ea80>{number = 7, name = (null)}

// 在点击屏幕时,我们继续去启动这个子线程去执行任务
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    NSLog(@"子线程地址:%@",self.thread);
    [self.thread start];
}

打印结果: 子线程地址:<WGThread: 0x6000038aef80>{number = 5, name = main}
接着程序crash了,  报错信息:Terminating app due to uncaught exception 'NSInvalidArgumentException',   
reason: '*** -[WGThread start]: attempt to start the thread again'

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor redColor];
    //1. 创建子线程
    WGThread *thread = [[WGThread alloc]initWithBlock:^{
        //2. 在子线程中添加NSTimer并将其添加到NSRunLoop中
        NSTimer *timer = [NSTimer timerWithTimeInterval:2.0 target:self   
        selector:@selector(timerChange) userInfo:nil repeats:YES];
        [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
        //3. 保住线程的命: 开启RunLoop循环,让它一直跑起来
        [[NSRunLoop currentRunLoop] run];
        //4 注意注意注意:下面的打印是不会被执行的,为什么? 因为RunLoop开启后是死循环,一直在处理循环里面的事件
        NSLog(@"当前线程是: %@", [NSThread currentThread]);
    }];
    [thread start];
}

-(void)timerChange{
    NSLog(@"timer来了");
}
    
打印结果: timer来了
        timer来了
         ...

//.m文件
@interface WGRunLoopVC ()
@property(nonatomic, assign) Boolean finish;  //声明个变量来控制进出死循环
@end

@implementation WGRunLoopVC

- (void)viewDidLoad {
    [super viewDidLoad];
    self.finish = NO;
    self.view.backgroundColor = [UIColor redColor];
    //1. 创建子线程
    WGThread *thread = [[WGThread alloc]initWithBlock:^{
        //2. 在子线程中添加NSTimer并将其添加到NSRunLoop中
        NSTimer *timer = [NSTimer timerWithTimeInterval:2.0 target:self   
        selector:@selector(timerChange) userInfo:nil repeats:YES];
        [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
        //3. 如果while里面是Yes就开始开启RunLoop, 直到遇到NO才退出RunLoop循环
        while (!self.finish) { 
            //每隔极短的时间就开启一次RunLoop
            [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:0.0001]];
        }
        //4. 当跳出循环后,下面的代码才会被执行
        NSLog(@"当前线程是: %@", [NSThread currentThread]);
    }];
    [thread start];
}

-(void)timerChange{
    NSLog(@"timer来了");
}

//点击屏幕时,我们让循环跳出
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    NSLog(@"点击屏幕了");
    self.finish = YES;
}

打印结果:  timer来了
          timer来了
          timer来了
          timer来了
          点击屏幕了
          当前线程是: <WGThread: 0x600003c216c0>{number = 6, name = (null)}
          线程WGThread已经销毁了

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [super touchesBegan:touches withEvent:event];
    //创建全局队列并添加异步任务
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
        NSLog(@"11111");
        /*
        1. 打印结果 11111  22222  33333
        分析: 该方法定义在NSObject.h文件中,就是正常的方法调用, 代码执行到这里就会去执行testPerform方法
        */
        //[self performSelector:@selector(testPerform) withObject:nil];
        
        /*
         2. 打印结果 11111 33333
        分析: 该方法定义在NSRunLoop.h文件中,该方法底层是设置一个Timer(定时器)事件源,但是当前子线程的RunLoop  
        默认是没有开启的所以,testPerform方法是不会被执行的, 无论afterDelay设置的时间是多少都不会被执行
        */
        //[self performSelector:@selector(testPerform) withObject:nil afterDelay:0];
        /*
         2.1 如果我们开启当前线程的RunLoop,那么打印结果就是 11111  22222  33333
         我们知道 [[NSRunLoop currentRunLoop] run]; 是个循环,为什么还会打印33333?  
         因为testPerform一旦执行完成,RunLoop中没有任务就会死掉,所以testPerform执行完成后跳出  
         RunLoop循环就接着打印了33333
         */
        //[[NSRunLoop currentRunLoop] run];
        
        /*
         3. 打印结果
         waitUntilDone: YES: 11111 22222 33333
                         NO: 11111 33333
         分析: 该方法定义在NSThread.h头文件中如果是YES,并且onThread和当前所在的线程是同一个线程,那么  
         就立马先执行testPerform后返回然后再接着往下执行; 如果是NO,那么该方法就依赖当前线程的RunLoop,  
         由于当前线程的RunLoop没有开启,所以testPerform不会执行
        */
        [self performSelector:@selector(testPerform) onThread:[NSThread currentThread]  
        withObject:nil waitUntilDone:NO];
        /*
         3.1 如果我们开启当前线程的RunLoop,那么waitUntilDone在设置为NO的情况下,打印结果如下: 11111 22222  
         [[NSRunLoop currentRunLoop] run]是循环, testPerform执行完成后RunLoop不应该销毁吗? (因为任务完成了)  
         为什么?⚠️: 这里有疑问, 暂时猜测此处的RunLoop开启会陷入一个死循环, 所以后续的信息33333就不会打印了
         */
        //[[NSRunLoop currentRunLoop] run];
        
        
        /* 3.2 开启RunLoop方法二
        如果没有输入源或者Timer事件添加到运行循环中,此方法将立即退出, 否则会重复调用该方法直到指定的时间到来
        因为我们设置了到指定的未来时间截止,所以该RunLoop开启后会一直运行
        我们也可以理解成死循环了 所以下面打印的结果就是: 11111 22222
        */
        //[[NSRunLoop currentRunLoop] runUntilDate:[NSDate distantFuture]];
        
        /* 3.3 开启RunLoop方法三
        如果没有输入源或者Timer事件添加到运行循环中,则此方法立即退出并返回NO,否则,将在处理完第一个输入源后或事件  
        到达后返回,所以下面打印的结果就是: 11111 22222 33333
        */
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
        NSLog(@"33333");
    });
}

-(void)testPerform{
    NSLog(@"22222");
}

//.h文件
@interface WGThread : NSThread
@end

@interface WGMainObjcVC : UIViewController
@end

//.m文件
@implementation WGThread
-(void)dealloc {
    NSLog(@"线程销毁了");
}
@end

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    WGThread *thread = [[WGThread alloc]initWithTarget:self   
    selector:@selector(change) object:nil];
    [thread start];
}
-(void)change {
    NSLog(@"线程中任务执行完成");
}
@end

打印结果: 线程中任务执行完成
        线程销毁了  

@interface WGMainObjcVC()
@property(nonatomic, strong) WGThread *thread;
@end

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    self.thread=[[WGThread alloc]initWithTarget:self selector:@selector(change) object:nil];
    [self.thread start];
}

-(void)change {
    NSLog(@"开始执行线程中的任务");
    //没有添加任何事件处理，直接run的话，RunLoop因为没有事件处理会立马退出 
    [[NSRunLoop currentRunLoop] run];
    NSLog(@"线程中任务执行完成");
}

//点击屏幕，继续向线程(self.thread)中添加任务
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self performSelector:@selector(newChange) onThread:self.thread   
    withObject:nil waitUntilDone:NO];
}
-(void)newChange {
    for (int i = 0; i < 3; i ++) {
        NSLog(@"----%d----",i);
    }
}
@end

打印结果: 开始执行线程中的任务
        线程中任务执行完成
点击屏幕的时候，并没有任何信息的打印

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    self.thread=[[WGThread alloc]initWithTarget:self selector:@selector(change) object:nil];
    [self.thread start];
}
-(void)change {
    NSLog(@"开始执行线程中的任务");
    //为RunLoop添加个Port(虽然什么都不处理),这样RunLoop就不会退出了
    [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
    //添加Port后，执行这句代码，由于没有事件处理，RunLoop会立即进入睡眠状态，等待有事件需要处理的时候会被再次唤醒
    //由于RunLoop处于休眠状态了，所以它下面的信息"线程中任务执行完成"就不会被打印了
    [[NSRunLoop currentRunLoop] run];
    NSLog(@"线程中任务执行完成");
}
//点击屏幕，继续向线程(self.thread)中添加任务
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self performSelector:@selector(newChange) onThread:self.thread  
    withObject:nil waitUntilDone:NO];
}
-(void)newChange {
    for (int i = 0; i < 3; i ++) {
        NSLog(@"----%d----",i);
    }
}

打印结果:开始执行线程中的任务
        ----0----
        ----1----
        ----2----

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    
    //创建线程方式一
    //self.thread = [[WGThread alloc]initWithTarget:self selector:@selector(change) object:nil];
    //[self.thread start];
    
    //创建线程方式二: 这种方式就不会造成self和thread的循环引用了，但是这种创建方式必须在iOS10以上才适合
    if (@available(iOS 10.0, *)) {
        self.thread = [[WGThread alloc] initWithBlock:^{
            NSLog(@"开始执行线程中的任务");
            [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
            [[NSRunLoop currentRunLoop] run];
            NSLog(@"线程中任务执行完成");
        }];
    } else {
        // Fallback on earlier versions
    }
    [self.thread start];
}

[[NSRunLoop currentRunLoop] run];

//.h文件
@interface WGThread : NSThread
@end

@interface WGMainObjcVC : UIViewController
@end

//.m文件
@implementation WGThread
-(void)dealloc {
    NSLog(@"WGThread线程销毁了");
}
@end

@interface WGMainObjcVC()
@property(nonatomic, strong) WGThread *thread;
@property(nonatomic, assign, getter=isStop)BOOL isStop; 添加一个Runloop退出的条件
@end

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor redColor];
    self.isStop = NO;
    __weak typeof(self) weakSelf = self;
    if (@available(iOS 10.0, *)) {
        self.thread = [[WGThread alloc] initWithBlock:^{
        
        NSLog(@"开始执行线程中的任务");
        [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
        //self强引用thread,thread强引用Block，Block内又引用self,weakSelf来避免循环引用
        while (!weakSelf.isStop) {
            //[NSDate distantFuture]表示未来某一不可达到的事件点，说白了等同与正无穷大的事件
            //beforeDat:过期时间，传入distantFuture遥远的未来，就是永远不会过期
            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:  
            [NSDate distantFuture]];
        }
        NSLog(@"线程中任务执行完成");
        }];
    } else { // Fallback on earlier versions }
    [self.thread start];
    UIButton *stopBtn = [[UIButton alloc]initWithFrame:CGRectMake(100, 100, 100, 40)];
    stopBtn.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:stopBtn];
    [stopBtn addTarget:self action:@selector(clickStopBtn)  
    forControlEvents:UIControlEventTouchUpInside];
}

-(void)clickStopBtn {
    /*
     🤔思考:为什么要放到self.thread执行停止Runloop的任务？
     因为一个线程对应一个Runloop对象，而我们要停止的是self.thread这个线程对应的Runloop对象 
     如果直接在这个方法中写停止Runloop，停止的是主线程中对应的Runloop对象
     */
    NSLog(@"点击了停止Runloop的按钮");
    [self performSelector:@selector(stopRunLoop) onThread:self.thread withObject:nil  
    waitUntilDone:NO];
}

-(void)stopRunLoop {
    self.isStop = YES;
    //系统提供的停止RunLoop的方法
    CFRunLoopStop(CFRunLoopGetCurrent());
}

//向self.thread线程中添加任务
-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self performSelector:@selector(newChange) onThread:self.thread withObject:nil  
    waitUntilDone:NO];
}

-(void)newChange {
    NSLog(@"开始执行添加到thread线程中的任务");
    for (int i = 0; i < 3; i ++) {
        NSLog(@"----%d----",i);
    }
}

-(void)dealloc {
    NSLog(@"WGMainObjcVC销毁了");
}
@end
    
打印结果: 开始执行线程中的任务                  (刚进入页面)
        开始执行添加到thread线程中的任务        (点击屏幕)
        ----0----
        ----1----
        ----2----
        点击了停止Runloop的按钮               (点击stopBtn按钮）
        线程中任务执行完成
        没有任何打印信息(说明Runloop已经被停止)  (点击屏幕)
        WGMainObjcVC销毁了                  (点击页面返回按钮)
        线程销毁了

//.m文件
@implementation WGThread
-(void)dealloc {
    NSLog(@"线程销毁了");
}
@end

@interface WGMainObjcVC()
@property(nonatomic, strong) WGThread *thread;
@property(nonatomic, assign, getter=isStop)BOOL isStop; 添加一个Runloop退出的条件
@end

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor redColor];
    self.isStop = NO;
    __weak typeof(self) weakSelf = self;
    if (@available(iOS 10.0, *)) {
        self.thread = [[WGThread alloc] initWithBlock:^{
        NSLog(@"开始执行线程中的任务");
        [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
        //self强引用thread,thread强引用Block，Block内又引用self,weakSelf来避免循环引用
        while (!weakSelf.isStop) {
            //[NSDate distantFuture]表示未来某一不可达到的时间点，说白了等同与正无穷大的事件
            //beforeDat:过期时间，传入distantFuture遥远的未来，就是永远不会过期
            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:  
            [NSDate distantFuture]];
        }
        NSLog(@"线程中任务执行完成");
        }];
    } else { /*Fallback on earlier versions*/ }
    [self.thread start];
}
-(void)dealloc {
    [self performSelector:@selector(stopRunLoop) onThread:self.thread   
    withObject:nil waitUntilDone:NO];
    NSLog(@"WGMainObjcVC销毁了");
}
-(void)stopRunLoop {
    NSLog(@"开始执行RunRunLoop停止的方法");
    self.isStop = YES;
    //系统提供的停止RunLoop的方法
    CFRunLoopStop(CFRunLoopGetCurrent());
    NSLog(@"执行RunRunLoop停止的方法已经结束了");
}
@end
    
打印结果: 开始执行线程中的任务              (进入页面)
        WGMainObjcVC销毁了              (返回页面)
        开始执行RunRunLoop停止的方法
        执行RunRunLoop停止的方法已经结束了
        程序crash -[WGMainObjcVC release]: message sent to deallocated instance 0x7fb2f6f06bb0

    -(void)dealloc {
        [self performSelector:@selector(stopRunLoop) onThread:self.thread withObject:nil waitUntilDone:YES];
        NSLog(@"WGMainObjcVC销毁了");
    }
    -(void)stopRunLoop {
        NSLog(@"开始执行RunRunLoop停止的方法");
        self.isStop = YES;
        //系统提供的停止RunLoop的方法
        CFRunLoopStop(CFRunLoopGetCurrent());
        NSLog(@"执行RunRunLoop停止的方法已经结束了");
    }
    打印结果: 开始执行线程中的任务                (进入页面)
            开始执行RunRunLoop停止的方法。      (退出页面)
            执行RunRunLoop停止的方法已经结束了
            WGMainObjcVC销毁了

//.m文件
@implementation WGThread
-(void)dealloc {
    NSLog(@"线程销毁了");
}
@end

@interface WGMainObjcVC()
@property(nonatomic, strong) WGThread *thread;
@property(nonatomic, assign, getter=isStop)BOOL isStop; 添加一个Runloop退出的条件
@end

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor redColor];
    self.isStop = NO;
    __weak typeof(self) weakSelf = self;
    if (@available(iOS 10.0, *)) {
        self.thread = [[WGThread alloc] initWithBlock:^{
        
        NSLog(@"开始执行线程中的任务");
        [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
        //self强引用thread,thread强引用Block，Block内又引用self,weakSelf来避免循环引用
        while (weakSelf && !weakSelf.isStop) {
            //[NSDate distantFuture]表示未来某一不可达到的事件点，说白了等同与正无穷大的事件
            //beforeDat:过期时间，传入distantFuture遥远的未来，就是永远不会过期
            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode   
            beforeDate:[NSDate distantFuture]];
        }
        NSLog(@"线程中任务执行完成");
        
        }];
    } else { /*Fallback on earlier versions*/ }
    [self.thread start];
    
    UIButton *stopBtn = [[UIButton alloc]initWithFrame:CGRectMake(100, 100, 100, 40)];
    stopBtn.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:stopBtn];
    [stopBtn addTarget:self action:@selector(stop) forControlEvents:UIControlEventTouchUpInside];
}

-(void)stop{
    [self performSelector:@selector(stopRunLoop) onThread:self.thread  
    withObject:nil waitUntilDone:YES];
}

-(void)stopRunLoop {
    NSLog(@"开始执行RunRunLoop停止的方法");
    self.isStop = YES;
    //系统提供的停止RunLoop的方法
    CFRunLoopStop(CFRunLoopGetCurrent());
    NSLog(@"执行RunRunLoop停止的方法已经结束了");
}

-(void)dealloc {
    [self stop];
    NSLog(@"WGMainObjcVC销毁了");
}
@end

打印结果: 开始执行线程中的任务                 (进入页面)
        开始执行RunRunLoop停止的方法         (点击stopBtn按钮)
        执行RunRunLoop停止的方法已经结束了
        线程中任务执行完成
        程序crash                          （退出页面）

//.m文件
@implementation WGThread
-(void)dealloc {
    NSLog(@"线程销毁了");
}
@end

@interface WGMainObjcVC()
@property(nonatomic, strong) WGThread *thread;
@property(nonatomic, assign, getter=isStop)BOOL isStop;  //添加一个Runloop退出的条件
@end

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor redColor];
    self.isStop = NO;
    __weak typeof(self) weakSelf = self;
    if (@available(iOS 10.0, *)) {
        self.thread = [[WGThread alloc] initWithBlock:^{
        
        NSLog(@"开始执行线程中的任务");
        [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
        //self强引用thread,thread强引用Block，Block内又引用self,weakSelf来避免循环引用
        while (weakSelf && !weakSelf.isStop) {
            //[NSDate distantFuture]表示未来某一不可达到的事件点，说白了等同与正无穷大的事件
            //beforeDat:过期时间，传入distantFuture遥远的未来，就是永远不会过期
            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode 
            beforeDate:[NSDate distantFuture]];
        }
        NSLog(@"线程中任务执行完成");
            
        }];
    } else { /*Fallback on earlier versions*/ }
    [self.thread start];
    
    UIButton *stopBtn = [[UIButton alloc]initWithFrame:CGRectMake(100, 100, 100, 40)];
    stopBtn.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:stopBtn];
    [stopBtn addTarget:self action:@selector(stop) forControlEvents:UIControlEventTouchUpInside];
}
-(void)stop{
    if (self.thread != nil) {
        [self performSelector:@selector(stopRunLoop) onThread:self.thread  
        withObject:nil waitUntilDone:YES];
    }
}
-(void)stopRunLoop {
    NSLog(@"开始执行RunRunLoop停止的方法");
    self.isStop = YES;
    //系统提供的停止RunLoop的方法
    CFRunLoopStop(CFRunLoopGetCurrent());
    NSLog(@"执行RunRunLoop停止的方法已经结束了");
    self.thread = nil;
}
-(void)dealloc {
    [self stop];
    NSLog(@"WGMainObjcVC销毁了");
}
@end

打印结果: 开始执行线程中的任务               (进入页面)
        开始执行RunRunLoop停止的方法       (点击stopBtn按钮)
        执行RunRunLoop停止的方法已经结束了   
        线程中任务执行完成
        线程销毁了                   
        WGMainObjcVC销毁了               (退出页面)
        
如果是进入页面后直接退出页面则打印结果如下
        开始执行线程中的任务                (进入页面)
        开始执行RunRunLoop停止的方法        (退出页面)
        执行RunRunLoop停止的方法已经结束了
        线程中任务执行完成
        WGMainObjcVC销毁了
        线程销毁了

//.h文件
@interface WGThread : NSThread
@end

typedef void (^WGHandle)(void);
//线程保活类
@interface WGKeepThreadAlive : NSObject

-(instancetype)init;
//在当前子线程下处理一个事件
-(void)handleEvent:(WGHandle)handle;
//停止当前线程对应的RunLoop循环并销毁线程
-(void)stopRunLoop;

@end

//.m文件
@implementation WGThread
-(void)dealloc {
    NSLog(@"线程销毁了");
}
@end

@interface WGKeepThreadAlive()
//这里可直接使用NSThread，使用WGThread只是为了验证线程是否销毁
//@property(nonatomic, strong) NSThread *thread;   
@property(nonatomic, strong) WGThread *thread;
@property(nonatomic, assign, getter=isStop) BOOL stop;
@end

//线程保活类
@implementation WGKeepThreadAlive

-(instancetype)init {
    if (self = [super init]) {
        self.stop = NO;
        __weak typeof(self)weakSelf = self;
        if (@available(iOS 10.0, *)) {
            self.thread = [[WGThread alloc]initWithBlock:^{
            
            //给当前线程对应的RunLoop对象添加基于端口的事件源
            [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
            //先判断，如果条件满足再执行循环体内的语句。
            //如果当前weakSelf不为nil，并且变量stop没有声明停止，就进入循环体
            while (weakSelf && !weakSelf.stop) {
                //如果当前线程下有在NSDefaultRunLoopMode运行模式下的事件，那么RunLoop就会启动并去处理；  
                如果没有事件，那么RunLoop就会处于休眠状态并在每过(多长时间)去启动一次该线程下的RunLoop
                [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:  
                [NSDate distantFuture]];
            }
                
            }];
            [self.thread start];
        } else { /*Fallback on earlier versions */ };
    }
    return self;
}

//在当前子线程下处理一个事件
-(void)handleEvent:(WGHandle)handle {
    if (self.thread != nil && handle != nil) {
        //此方法可以传递参数，将参数放在withObject中;waitUntilDone:NO处理任务的时候，这里不需要等待  
        子线程中的任务执行完成，即仍然异步执行
        [self performSelector:@selector(privateHandleEventInThread:)   
        onThread:self.thread withObject:handle waitUntilDone:NO];
    }
}
-(void)privateHandleEventInThread:(WGHandle)handle{
    handle();
}

//停止当前线程对应的RunLoop循环并销毁线程
-(void)stopRunLoop {
    if (self.thread != nil) {
        [self performSelector:@selector(privateStop) onThread:self.thread  
        withObject:nil waitUntilDone:YES];
    }
}
-(void)privateStop {
    self.stop = YES;
    CFRunLoopStop(CFRunLoopGetCurrent());
    self.thread = nil;
}

//对象销毁的时候停止RunLoop并销毁线程
-(void)dealloc {
    [self stopRunLoop];
    NSLog(@"对象销毁了");
}
@end

调用验证

//.h文件
@interface WGMainObjcVC()
@property(nonatomic, strong) WGKeepThreadAlive *alive;
@end

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor redColor];
    self.alive =[[WGKeepThreadAlive alloc]init];
    [self.alive handleEvent:^{
        NSLog(@"当前线程是:%@---我的名字叫张三",[NSThread currentThread]);
    }];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self.alive stopRunLoop];
}

//进入页面->点击屏幕->退出页面
打印结果: 当前线程是:<WGThread: 0x600001a80a00>{number = 6, name = (null)}---我的名字叫张三
        线程销毁了
        对象销毁了

//进入页面->退出页面
打印结果: 当前线程是:<WGThread: 0x600001a94cc0>{number = 8, name = (null)}---我的名字叫张三
        对象销毁了
        线程销毁了

//.m文件
@interface WGMainObjcVC() <UIScrollViewDelegate>
@property(nonatomic, strong) UIScrollView *scrollView;
@property(nonatomic, strong) NSTimer *timer;
@end

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    self.scrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 80,   
    UIScreen.mainScreen.bounds.size.width, 300)];
    
    self.scrollView.contentSize = CGSizeMake(UIScreen.mainScreen.bounds.size.width,  
    UIScreen.mainScreen.bounds.size.height * 2);
    
    self.scrollView.delegate = self;
    self.scrollView.backgroundColor = [UIColor redColor];
    [self.view addSubview:self.scrollView];
    
    //定时器启动方式一：需要手动将定时器添加到RunLoop中的NSDefaultRunLoopMode运行模式下
    self.timer = [NSTimer timerWithTimeInterval:2.0 target:self   
    selector:@selector(timeChange) userInfo:nil repeats:YES];
    [[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSDefaultRunLoopMode];
    [self.timer fire];
    /*定时器启动方式二：默认将定时器添加到RunLoop中的NSDefaultRunLoopMode运行模式下了
    self.timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self  
    selector:@selector(timeChange) userInfo:nil repeats:YES];
    [self.timer fire];
    */
}
-(void)timeChange {
    NSLog(@"定时器执行任务---当前的Runloop运行的模式是:%@",[NSRunLoop currentRunLoop].currentMode);
}
-(void)scrollViewDidScroll:(UIScrollView *)scrollView {
    NSLog(@"开始滚动---当前的Runloop运行的模式是:%@",[NSRunLoop currentRunLoop].currentMode);
}
@end

打印结果: 10:03:14.051210+0800 定时器执行任务---当前的Runloop运行的模式是:kCFRunLoopDefaultMode
        10:03:16.052367+0800  定时器执行任务---当前的Runloop运行的模式是:kCFRunLoopDefaultMode
        10:03:18.052332+0800  定时器执行任务---当前的Runloop运行的模式是:kCFRunLoopDefaultMode
        10:03:18.219758+0800  开始滚动---当前的Runloop运行的模式是:UITrackingRunLoopMode
        10:03:19.475690+0800  开始滚动---当前的Runloop运行的模式是:UITrackingRunLoopMode
        10:03:20.860416+0800  开始滚动---当前的Runloop运行的模式是:UITrackingRunLoopMode
        10:03:21.054855+0800  开始滚动---当前的Runloop运行的模式是:UITrackingRunLoopMode
        10:03:22.723441+0800  开始滚动---当前的Runloop运行的模式是:UITrackingRunLoopMode

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    self.scrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 80, 
    UIScreen.mainScreen.bounds.size.width, 300)];
    
    self.scrollView.contentSize = CGSizeMake(UIScreen.mainScreen.bounds.size.width,
    UIScreen.mainScreen.bounds.size.height * 2);
    
    self.scrollView.delegate = self;
    self.scrollView.backgroundColor = [UIColor redColor];
    [self.view addSubview:self.scrollView];
    
    //定时器启动方式一：需要手动将定时器添加到RunLoop中的NSDefaultRunLoopMode运行模式下
    self.timer = [NSTimer timerWithTimeInterval:2.0 target:self selector:@selector(timeChange)  
    userInfo:nil repeats:YES];
    //[[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSDefaultRunLoopMode];
    //将定时器添加到RunLoop运行循环中的NSRunLoopCommonModes运行模式下
    [[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];
    [self.timer fire];

    /*定时器启动方式二：默认将定时器添加到RunLoop中的NSDefaultRunLoopMode运行模式下了
    self.timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self   
    selector:@selector(timeChange) userInfo:nil repeats:YES];
    
    [[NSRunLoop currentRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];
    [self.timer fire];
    */
}

-(void)timeChange {
    NSLog(@"定时器执行任务---当前的Runloop运行的模式是:%@",[NSRunLoop currentRunLoop].currentMode);
}

-(void)scrollViewDidScroll:(UIScrollView *)scrollView {
    NSLog(@"开始滚动---当前的Runloop运行的模式是:%@",[NSRunLoop currentRunLoop].currentMode);
}

打印结果: 10:36:42.809265+0800  定时器执行任务---当前的Runloop运行的模式是:kCFRunLoopDefaultMode
    10:36:44.809261+0800  定时器执行任务---当前的Runloop运行的模式是:kCFRunLoopDefaultMode
    10:36:46.523926+0800  开始滚动---当前的Runloop运行的模式是:UITrackingRunLoopMode
    10:36:46.580310+0800  开始滚动---当前的Runloop运行的模式是:UITrackingRunLoopMode
    10:36:46.637176+0800  开始滚动---当前的Runloop运行的模式是:UITrackingRunLoopMode
    10:36:46.717130+0800  开始滚动---当前的Runloop运行的模式是:UITrackingRunLoopMode
    10:36:46.808626+0800  定时器执行任务---当前的Runloop运行的模式是:UITrackingRunLoopMode
    10:36:46.830735+0800  开始滚动---当前的Runloop运行的模式是:UITrackingRunLoopMode
    10:36:47.285391+0800  开始滚动---当前的Runloop运行的模式是:UITrackingRunLoopMode

CFRunLoopObserverRef这是一个观察者，主要用途就是监听RunLoop的状态变化
/* Run Loop Observer Activities */
typedef CF_OPTIONS(CFOptionFlags, CFRunLoopActivity) {
    kCFRunLoopEntry = (1UL << 0),            进入RunLoop
    kCFRunLoopBeforeTimers = (1UL << 1),     (即将处理Timers)触发 Timer 回调
    kCFRunLoopBeforeSources = (1UL << 2),    (即将处理Sources)触发 Source0 回调
    kCFRunLoopBeforeWaiting = (1UL << 5),    (即将进入休眠)等待 mach_port 消息
    kCFRunLoopAfterWaiting = (1UL << 6),     (刚从休眠中唤醒)接收 mach_port 消息
    kCFRunLoopExit = (1UL << 7),             退出RunLoop
    kCFRunLoopAllActivities = 0x0FFFFFFFU    loop 所有状态改变
};

    /* Run Loop Observer Activities */
    typedef CF_OPTIONS(CFOptionFlags, CFRunLoopActivity) {
        kCFRunLoopEntry = (1UL << 0),          //即将进入Loop
        kCFRunLoopBeforeTimers = (1UL << 1),   //即将处理Timer
        kCFRunLoopBeforeSources = (1UL << 2),  //即将处理Sources
        kCFRunLoopBeforeWaiting = (1UL << 5),  //即将进入休眠
        kCFRunLoopAfterWaiting = (1UL << 6),   //刚从休眠中唤醒
        kCFRunLoopExit = (1UL << 7),           //即将退出Loop
        kCFRunLoopAllActivities = 0x0FFFFFFFU  //所有状态
    };

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    //kCFRunLoopCommonModes: 默认包含 kCFRunLoopDefaultMode + UITrackingRunLoopMode
    //1.创建observer
    CFRunLoopObserverRef observer = CFRunLoopObserverCreate(kCFAllocatorDefault,  
    kCFRunLoopAllActivities, YES, 0, CFRunLoopObserverCallBack1, NULL);
    //1.1 创建observer的第二种方法: 将监听方法放到Block中去
    CFRunLoopObserverRef observer1 = CFRunLoopObserverCreateWithHandler(kCFAllocatorDefault,  
    kCFRunLoopAllActivities,YES,0,^(CFRunLoopObserverRef observer, CFRunLoopActivity activity){
    });
    
    //2.添加observer到RunLoop
    CFRunLoopAddObserver(CFRunLoopGetCurrent(), observer, kCFRunLoopCommonModes);
    
    //3.释放observer
    CFRelease(observer);
}
    
// 监听到RunLoop状态改变
void CFRunLoopObserverCallBack1(CFRunLoopObserverRef observer,CFRunLoopActivity activity,void *info){
    switch (activity) {
        case kCFRunLoopEntry: {
            CFRunLoopMode mode = CFRunLoopCopyCurrentMode(CFRunLoopGetCurrent());
            NSLog(@"kCFRunLoopEntry-----运行模式:%@",mode);
            CFRelease(mode); //mode是需要释放的
            break;
        }
        case kCFRunLoopExit:
            NSLog(@"kCFRunLoopExit");
            break;
        case kCFRunLoopBeforeSources:
            NSLog(@"kCFRunLoopBeforeSources");
            break;
        case kCFRunLoopBeforeTimers:
            NSLog(@"kCFRunLoopBeforeTimers");
            break;
        case kCFRunLoopBeforeWaiting:
            NSLog(@"kCFRunLoopBeforeWaiting");
            break;
        case kCFRunLoopAfterWaiting:
            NSLog(@"kCFRunLoopAfterWaiting");
            break;
        default:
            break;
    }
}

@interface WGMainObjcVC()
@property(nonatomic, strong) WGThread *thread;
@end

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    /*这种创建线程的方式+ NSRunLoop的run方法 会导致循环引用: 
    VC->Thread(属性)  Thread->VC(initWithTarget:self)
    */
    self.thread=[[WGThread alloc]initWithTarget:self selector:@selector(task) object:nil];
    [self.thread start];
}

-(void)tesk{
    /* 保住线程:  
    1.子线程中任务执行完成就会结束,线程就会销毁,所以要让子线程中一直有任务
    2.首先在子线程中添加任务到RunLoop,没有任务(Timers/Sources/Observers)RunLoop就会退出,线程就会销毁;
    3.运行RunLoop
     */
    [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
    [[NSRunLoop currentRunLoop] run];
    NSLog(@"-----%s-----%@",__func__,[NSThread currentThread]);
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    //这种方式下创建线程,线程和VC之间就不会相互引用,VC能销毁了,但是线程不会销毁
    self.thread = [[WGThread alloc]initWithBlock:^{
        NSLog(@"-----start-----");
        [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
        [[NSRunLoop currentRunLoop] run];
        //为什么VC销毁了,线程却不会被销毁?
        //因为启动线程后,RunLoop如果有任务就会执行,没有任务就会休眠,线程会一直卡在这个地方,
        //所以线程不会销毁,下面的代码也不会执行
        NSLog(@"-----end-----");
    }];
    [self.thread start];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self performSelector:@selector(task) onThread:self.thread  
    withObject:nil waitUntilDone:NO];
}

-(void)task {
    NSLog(@"-----%s-----%@",__func__,[NSThread currentThread]);
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    //这种方式下创建线程,线程和VC之间就不会相互引用,VC能销毁了,但是线程不会销毁
    self.thread = [[WGThread alloc]initWithBlock:^{
        [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
        [[NSRunLoop currentRunLoop] run];
        NSLog(@"-----end-----");
    }];
    [self.thread start];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self performSelector:@selector(task) onThread:self.thread withObject:nil waitUntilDone:NO];
}

-(void)task {
    NSLog(@"-----%s-----%@",__func__,[NSThread currentThread]);
}

/// 停止RunLoop
-(void)stop{
    //停止RunLoop,OC语法的NSRunLoop没有提供stop的API,所以只能用C语言的
    CFRunLoopStop(CFRunLoopGetCurrent());
}

-(void)dealloc {
    //必须是停掉子线程的RunLoop
    [self performSelector:@selector(stop) onThread:self.thread withObject:nil waitUntilDone:NO];
    NSLog(@"-----%s",__func__);
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    //这种方式下创建线程,线程和VC之间就不会相互引用,VC能销毁了,但是线程不会销毁
    self.thread = [[WGThread alloc]initWithBlock:^{
        [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
        NSLog(@"-----end-----");
    }];
    [self.thread start];
}

@interface WGMainObjcVC()
@property(nonatomic, strong) WGThread *thread;
@property(nonatomic, assign, getter=isStop) BOOL stop;
@end

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    self.stop = NO;
    __weak typeof(self) weakSelf = self;
    self.thread = [[WGThread alloc]initWithBlock:^{
        [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
        //这里必须用弱引用,防止线程和VC相互引用
        while (!weakSelf.stop) {
            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
        }
        NSLog(@"-----end-----");
    }];
    [self.thread start];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self performSelector:@selector(task) onThread:self.thread withObject:nil waitUntilDone:NO];
}

-(void)task {
    NSLog(@"-----%s-----%@",__func__,[NSThread currentThread]);
}

-(void)stop{
    //设置标记为YES
    self.stop = YES;
    CFRunLoopStop(CFRunLoopGetCurrent());
}

-(void)dealloc {
    //当控制器销毁时,停掉RunLoop,  
    [self performSelector:@selector(stop) onThread:self.thread withObject:nil waitUntilDone:NO];
}

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    self.stop = NO;
    __weak typeof(self) weakSelf = self;
    self.thread = [[WGThread alloc]initWithBlock:^{
        [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
        while (!weakSelf.stop) {
            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
        }
        NSLog(@"-----end-----");
    }];
    [self.thread start];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [self performSelector:@selector(task) onThread:self.thread withObject:nil waitUntilDone:NO];
}

-(void)task {
    NSLog(@"-----%s-----%@",__func__,[NSThread currentThread]);
}

-(void)stop{
    //设置标记为YES
    self.stop = YES;
    CFRunLoopStop(CFRunLoopGetCurrent());
}

-(void)dealloc {
    // waitUntilDone:YES代表子线程的代码执行完毕后,这个方法才会继续往下走
    [self performSelector:@selector(stop) onThread:self.thread withObject:nil waitUntilDone:YES];
}

@interface WGMainObjcVC()
@property(nonatomic, strong) WGThread *thread;
@property(nonatomic, assign, getter=isStop) BOOL stop;
@end

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    self.stop = NO;
    __weak typeof(self) weakSelf = self;
    self.thread = [[WGThread alloc]initWithBlock:^{
        [[NSRunLoop currentRunLoop] addPort:[[NSPort alloc]init] forMode:NSDefaultRunLoopMode];
        while (weakSelf && !weakSelf.stop) {
            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
        }
        NSLog(@"-----end-----");
    }];
    [self.thread start];
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    if (!self.thread) {  //如果thread为nil就直接返回
        return;
    }
    [self performSelector:@selector(task) onThread:self.thread withObject:nil waitUntilDone:NO];
}

-(void)task {
    NSLog(@"-----%s-----%@",__func__,[NSThread currentThread]);
}

-(void)stop{
    self.stop = YES;
    CFRunLoopStop(CFRunLoopGetCurrent());
    // 清空Thread
    self.thread = nil;
}

-(void)dealloc {
    if (!self.thread) {  //如果thread为nil就直接返回
        return;
    }
    [self performSelector:@selector(stop) onThread:self.thread withObject:nil waitUntilDone:YES];
}