#import "Model.h"

#import "DataViewController.h"

@interface Model ()

@property (nonatomic, strong, readonly) NSArray *days;

@property (nonatomic, strong, readonly) NSArray *quotes;

@implementation Model

- (instancetype)init {

self = [super init];

if (self) {

// 创建数据模型。

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];

_days = [[dateFormatter weekdaySymbols] copy];

_quotes = @[@"Everyone who isn’t us is an enemy.",

@"When you play the game of thrones you win or you die. There is no middle ground.",

@"You’re a clever man. But you’re not half as clever as you think you are.",

@"Nobody cares what your father once told you.",

@"Everywhere in the world, they hurt little girls.",

@"I choose violence.",

@"What is Dead May Never Die"

];

}

return self;

}

- (DataViewController *)viewControllerAtIndex:(NSUInteger)index {

// 返回指定index的视图控制器。

if (self.days.count == 0 || index >= self.days.count) {

return nil;

}

DataViewController *dataVC = [[DataViewController alloc] init];

dataVC.itemIndex = index;

dataVC.day = self.days[index];

dataVC.quote = self.quotes[index];

return dataVC;

}

#pragma mark - UIPageViewControllerDataSource

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {

// 返回上一个视图控制器。

NSUInteger index = ((DataViewController *)viewController).itemIndex;

if (index == 0 || index == NSNotFound) {

return nil;

}

--index;

return [self viewControllerAtIndex:index];

}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {

// 返回下一个视图控制器。

NSUInteger index = ((DataViewController *)viewController).itemIndex;

if (index == self.days.count - 1 || index == NSNotFound) {

return nil;

}

++index;

return [self viewControllerAtIndex:index];

}

- (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController {

NSUInteger currentPage = 2;

if (currentPage >= self.days.count) {

currentPage = 0;

}

DataViewController *dataVC = (DataViewController *)pageViewController.viewControllers.firstObject;

dataVC.itemIndex = currentPage;

dataVC.day = self.days[currentPage];

dataVC.quote = self.quotes[currentPage];

return currentPage;

}

- (NSInteger)presentationCountForPageViewController:(UIPageViewController *)pageViewController {

return self.days.count;

}