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![Login button enabled state
let signUpActiveSignal = RACSignalEx.combineLatestAs(
[validUsernameSignal, validPasswordSignal]) {
(validUsername: NSNumber, validPassword: NSNumber) -> NSNumber in
return validUsername && validPassword
}
!
signUpActiveSignal.subscribeNextAs {
(active: NSNumber) in
self.signInButton.enabled = active
}
Combines two signals into a new one](https://image.slidesharecdn.com/reactivecocoamadesimplewithswift-140903104512-phpapp02/75/Reactive-cocoa-made-Simple-with-Swift-26-2048.jpg)
![[[[[[[[self requestAccessToTwitterSignal]
then:^RACSignal *{
@strongify(self)
return self.searchText.rac_textSignal;
}]
filter:^BOOL(NSString *text) {
@strongify(self)
return [self isValidSearchText:text];
}]
throttle:0.5]
flattenMap:^RACStream *(NSString *text) {
@strongify(self)
return [self signalForSearchWithText:text];
}]
deliverOn:[RACScheduler mainThreadScheduler]]
subscribeNext:^(NSDictionary *jsonSearchResult) {
NSArray *statuses = jsonSearchResult[@"statuses"];
NSArray *tweets = [statuses linq_select:^id(id tweet) {
return [RWTweet tweetWithStatus:tweet];
}];
[self.resultsViewController displayTweets:tweets];
} error:^(NSError *error) {
NSLog(@"An error occurred: %@", error);
}];](https://image.slidesharecdn.com/reactivecocoamadesimplewithswift-140903104512-phpapp02/75/Reactive-cocoa-made-Simple-with-Swift-37-2048.jpg)
Uploaded byColin Eberhardt
Reactive cocoa made Simple with Swift
ReactiveCocoa is a framework for building reactive applications using signals that emit events. It allows defining data flows where events are propagated through operations like map, filter, and flatten. Signals can represent UI controls, network requests, or other asynchronous events. This allows building reactive user interfaces where UI is updated automatically in response to data changes. Operations are chained fluently on signals to transform and combine events.
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Reactive cocoa made Simple with Swift
- 1. ReactiveCocoa made Simplewith Swift! @ColinEberhardt ShinobiControls
- 2.
- 3. What is ReactiveCocoa? • ReactiveCocoa is an open-source framework created by the GitHub team • Inspired by Functional Reactive Programming (FRP) • Changes the way in which we structure our applications • Inspired by Microsoft’s ReactiveExtensions (Rx)
- 4. Functional Reactive Programming • Functional Programming • First-class functions, passed as arguments to other functions • Reactive Programming • Focusses on data flow • Functional Programming + Reactive Programming = FRP
- 5. FRP - WTF? http://stackoverflow.com/questions/1028250/what-is-functional-reactive-programming
- 6. In my ownwords … • Every line of code we write is executed in reaction to an event • But … these events all have different interfaces • delegates, target-action, KVO, closures • ReactiveCocoa provides a standard interface for all events • Allows us to define a higher level language • Easier to test too!
- 7.
- 8. Code Build Run Explain! Repeat
- 9. Get Reactive lettextSignal: RACSignal = usernameTextField.rac_textSignal() ! textSignal.subscribeNext { (text: AnyObject!) -> Void in let textString = text as String println(textString) }
- 10. Simplified with Swift func subscribeNextAs<T>(nextClosure:(T) -> ()) -> () { self.subscribeNext { (next: AnyObject!) -> () in let nextAsT = next! as T nextClosure(nextAsT) } } textSignal.subscribeNextAs { (text: String) -> () in println(text) }
- 11. Signals! • Asignal emits events • next • error • completed • A signal can have none, one or more subscribers textSignal.subscribeNextAs({ (text: String) in println(text) }, error: { (error) in // ... }, completed: { // ... })
- 12. Events Signals canemit none, one or more next events, optionally followed by either an error or completed COMPLETED NEXT NEXT ERROR NEXT NEXT NEXT NEXT … intervals do not have to be regular!
- 13. Signal all things • Network request • A single next, followed by a completed • Large download • Multiple next events, representing partial data, followed by completed • UI control • An infinite stream of next events
- 14. Operations • ReactiveCocoaallows you to perform operations on signals • map, filter, skip, take, throttle … • These operations are entirely agnostic to the source of the signal
- 15. filter let textSignal:RACSignal = usernameTextField.rac_textSignal() ! let filteredText = textSignal.filterAs { (text: NSString) -> Bool in return text.length > 3 } ! filteredText.subscribeNextAs { (text: String) in println(text) } A filter is a ‘gate’, filtering-out events which do not match the given condition
- 16. What exactly areevents? • What does a next event actually look like? • Anything! • Signals are an interface for handling asynchronous events • The event contents is context dependant
- 17. map let textSignal:RACSignal = usernameTextField.rac_textSignal() ! let textLength = textSignal.mapAs { (text: NSString) -> NSNumber in return text.length } ! textLength.subscribeNextAs { (length: NSNumber) in println(length) } Transforms each next event
- 18. Creating a pipeline let textSignal: RACSignal = usernameTextField.rac_textSignal() ! let textLength = textSignal.mapAs { (text: NSString) -> NSNumber in return text.length } ! let filteredText = textLength.filterAs { (number: NSNumber) -> Bool in return number > 3 } ! filteredText.subscribeNextAs { (length: NSNumber) in println(length) }
- 19. Fluent syntax usernameTextField.rac_textSignal() .mapAs { (text: NSString) -> NSNumber in return text.length }.filterAs { (number: NSNumber) -> Bool in return number > 3 }.subscribeNextAs { (length: NSNumber) in println(length) } Operations return RACSignal, allowing method chaining
- 20. rac_textSignal() .mapAs { (text: NSString) -> NSNumber in return text.length }.filterAs { (number: NSNumber) -> Bool in return number > 3 }.subscribeNextAs { (length: NSNumber) in println(length) } Value->-3- rac_textSIgnal- map- filter- subscribeNext- NSString- NSNumber-usernameTextField.
- 21. Valid text fields let validUsernameSignal = usernameTextField.rac_textSignal() .mapAs { (text: NSString) -> NSNumber in return self.isValidUsername(text) } ! validUsernameSignal.mapAs { (valid: NSNumber) -> UIColor in return valid.boolValue ? UIColor.clearColor() : UIColor.yellowColor() }.setKeyPath("backgroundColor", onObject: usernameTextField) • Unfortunately we need to ‘box’ bool values. • I am sure ReactiveSwift will fix this ;-)
- 22. More Swift Magic! !! RAC(usernameTextField, "backgroundColor") << validUsernameSignal.mapAs { (valid: NSNumber) -> UIColor in return valid.boolValue ? UIColor.clearColor() : UIColor.yellowColor() } http://napora.org/a-swift-reaction/
- 23. More Sweet SweetSwift! func validToBackground(valid: NSNumber) -> UIColor { return valid.boolValue ? UIColor.clearColor() : UIColor.yellowColor() } ! func isValidText(validator:(String) -> Bool)(text: NSString) -> NSNumber { return validator(text) } ! let validUsernameSignal = usernameTextField.rac_textSignal() .mapAs(isValidText(isValidUsername)) .distinctUntilChanged() ! RAC(usernameTextField, "backgroundColor") << validUsernameSignal.mapAs(validToBackground)
- 26. Login button enabledstate let signUpActiveSignal = RACSignalEx.combineLatestAs( [validUsernameSignal, validPasswordSignal]) { (validUsername: NSNumber, validPassword: NSNumber) -> NSNumber in return validUsername && validPassword } ! signUpActiveSignal.subscribeNextAs { (active: NSNumber) in self.signInButton.enabled = active } Combines two signals into a new one
- 27. The pipeline NSString-BOOL- UIColor-password-rac_ rac_textSIgnal- map- map- backgroundColor- BOOL- reduce- subscribeNext- NSString- BOOL- UIColor-username-combineLatest: textSIgnal- map- map- backgroundColor-
- 28. Reactive Button Click signInButton.rac_signalForControlEvents(.TouchUpInside) .subscribeNext { (button) in println("clicked") } Replaces target-action with a signal
- 29. Creating Signals funcsignInSignal() -> RACSignal { return RACSignal.createSignal { (subscriber) -> RACDisposable! in println("Sign-in initiated") self.signInService.signInWithUsername(self.usernameTextField.text, password: self.passwordTextField.text) { (success) in println("Sign-in completed") subscriber.sendNext(success) subscriber.sendCompleted() } return nil } }
- 30. Using the sign-insignal signInButton.rac_signalForControlEvents(.TouchUpInside) .map { (any) -> RACSignal in self.signInSignal() }.subscribeNext { (any) in println(any) }
- 31. Doing it right! signInButton.rac_signalForControlEvents(.TouchUpInside) .flattenMap { (any) -> RACSignal in self.signInSignal() }.subscribeNext { (any) in println(any) } flattenMap subscribes to a signal, returning the resultant events
- 32. Side-effects signInButton.rac_signalForControlEvents(.TouchUpInside) .doNext{ (any) in self.signInButton.enabled = false; }.flattenMap { (any) -> RACSignal in self.signInSignal() }.subscribeNextAs { (success: NSNumber) in self.signInButton.enabled = true; self.handleSignInResult(success.boolValue) } Side-effects receive next events, but cannot mutate them
- 33. Login pipeline doNext1 signInSignal1 BOOL1 UIBu3on1 BOOL1 rac_signalForControlEvents11 fla3enMap1 subscribeNext1
- 34. ReactiveCocoa Made Simple • A signal emits events • next • error • completed • A signal can have multiple subscribers • Signals can emit multiple next events, optionally followed by either an error or completed
- 35.
- 37. [[[[[[[self requestAccessToTwitterSignal] then:^RACSignal*{ @strongify(self) return self.searchText.rac_textSignal; }] filter:^BOOL(NSString *text) { @strongify(self) return [self isValidSearchText:text]; }] throttle:0.5] flattenMap:^RACStream *(NSString *text) { @strongify(self) return [self signalForSearchWithText:text]; }] deliverOn:[RACScheduler mainThreadScheduler]] subscribeNext:^(NSDictionary *jsonSearchResult) { NSArray *statuses = jsonSearchResult[@"statuses"]; NSArray *tweets = [statuses linq_select:^id(id tweet) { return [RWTweet tweetWithStatus:tweet]; }]; [self.resultsViewController displayTweets:tweets]; } error:^(NSError *error) { NSLog(@"An error occurred: %@", error); }];
- 39.
- 41. // a signalthat emits events when visibility changes let visibleStateChanged = RACObserve(self, "isVisible").skip(1) ! // filtered into visible and hidden signals let visibleSignal = visibleStateChanged.filter { $0.boolValue } let hiddenSignal = visibleStateChanged.filter { !$0.boolValue } ! // a signal that emits when an item has been visible for 1 second let fetchMetadata = visibleSignal.delay(1).takeUntil(hiddenSignal) ! fetchMetadata.subscribeNext { (next: AnyObject!) -> () in // fetch data }
- 42. Resources • https://github.com/ReactiveCocoa/ReactiveCocoa • Read the Change Logs! • My Stuff … • http://www.raywenderlich.com/u/ColinEberhardt • https://github.com/ColinEberhardt • The code from this presentation • https://github.com/ColinEberhardt/ SwiftReactivePlayground
- 43. ReactiveCocoa made Simplewith Swift! @ColinEberhardt ShinobiControls