Introduction to ReactiveCocoa and FRP by Alexander Zaporozhchenko

Introduction to ReactiveCocoa and FRP by Alexander Zaporozhchenko

Transcript

1. Введение в ReactiveCocoa и FRP Запорожченко Александр компания Ecodery, iOS Developer
2. Что такое FRP? Реактивное программирование: • потоки данных • распространение данных • реакция на events Функциональный подход: • набор функций • отсутствие состояний и мутабельности • зависимость только от входных данных FRP = (Reactive + Functional) Programming;
3. Imperative Reactive x = 2; y = 3; z = x + y; // z = 5 x = 1; // z = 5 y = -10; // z = 5 x = 2; y = 3; z = x + y; // z = 5 x = 1; // z = 3 y = -10; // z = -8
4. NSMutableArray *returnArray = [NSMutableArray new]; for (NSString *string in array) { if ([string hasPrefix:@"RAC"]) { [returnArray addObject:[string stringByReplacingOccurrencesOfString:@"RAC" withString:@""]]; } NSArray *sampleArray = [[[array.rac_sequence filter:^BOOL(NSString *string) { return [string hasPrefix:@"RAC"]; }] map:^(NSString *string) { return [string stringByReplacingOccurrencesOfString:@"RAC" withString:@""]; }] array]; //(Simple, Reactive, Functional, Programming) Imperative Functional NSArray *array = @[@"RACSimple", @"Imperative", @" ", @"RACReactive", @"RACFunctional", @"RACProgramming"];
5. Что за ReactiveCocoa? ReactiveCocoa: 1. Open-source GitHub framework 2. Реализует парадигму FRP для iOS/OSX 3. 2.5 версия Objc, 3.0 версия Swift 4. Carthage / submodules / unofficial pod 5. RACStream
7. RACSequence 1. Pull-driven stream 2. About working with collections RACSequence *letters = [@"A B C D E F G H I" componentsSeparatedByString:@" "].rac_sequence; // Contains: AA BB CC DD EE FF GG HH II RACSequence *mapped = [letters map:^(NSString *value) { return [value stringByAppendingString:value]; }];
8. RACSignal 1. Push-driven stream of values 2. Events : Next, Completed, Error 3. One or more Subscribers 4. Operations: Subscribing, Side-effects, Transformation, Combining, Control 5. Signals are cold // RACObserve(self, username) creates a new RACSignal [RACObserve(self, username) subscribeNext:^(NSString *newName) { NSLog(@"%@", newName); }];
9. Basic operators Subscriptions: subscribeNext subscribeCompleted subscribeError Side-effects: doCompleted doNext doError doDisposed Transforming: map filter Combining: concat merge flattenMap then combineLatest switchToLatest Control: skip takeUntil throttle
10. Observe [RACObserve(self.viewModel, recipeName) subscribeNext:^(NSString *string) { //... }]; [[RACObserve(self.viewModel, recipeName) filter:^BOOL(NSString *string) { return (string.length > 10); }] subscribeNext:^(NSString *string) { NSLog(@"RecipeName : %@", string); //... }];
11. Bindings RAC(self, titleLabel.text) = RACObserve(self, model.title); RAC(self.startButton, enabled) = RACObserve(self.viewModel, canStartTimer); RAC(self.viewModel, stepName) = self.stepNameTextField.rac_textSignal; RAC(self, titleLable.text) = [RACObserve(self, model.title) map:^id(NSString *text) { return [NSString stringWithFormat:@”Title: %@”, text]; }];
12. Operations on collections RACSequence *goodPlayersArray = [[[playersArray rac_sequence] filter:^BOOL(MatchViewModel *match) { return (player.goals > 5); }] map:^id(Player *player) { return player.name; }]; NSArray *myArray = [NSArray new]; [myArray enumerateObjectsUsingBlock:^(id anObject, NSUInteger idx, BOOL *stop) { //... }];
13. [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) { __block NSURLSessionDataTask *task = [self GET:url parameters:parameters completion:^(id response, NSError *error) { if (!error) { [subscriber sendNext:response]; [subscriber sendCompleted]; } else { [subscriber sendError:error]; } }]; return [RACDisposable disposableWithBlock:^{ [task cancel]; }]; }]]; Networking
14. Where to go from here? https://gist.github.com/JaviLorbada/4a7bd6129275ebefd5a6 The best FRP in iOS links. https://github.com/ReactiveCocoa/ReactiveCocoa/tree/core-legacy- objc/Documentation ReactiveCocoa Objective-C Documentation