ReactiveCocoa

My talk for UIKonf 2013 about ReactiveCocoa and how to get rid of state

Transcript

1. ReactiveCocoa OR: How I stopped worrying about state and love FRP
2.  ✉   robb robb@robb.is tmp ceterum_censeo
3. Let’s talk about State
4. evil √
5. Have you tried turning it off and on again?
6. Have you tried turning it off and on again? Have you tried turning it off and on again?
7. state
8. @property (readwrite, …) BOOL quacksLikeADuck; @property (readwrite, …) BOOL walksLikeADuck; @property (readonly, …) BOOL probablyADuck;
9. + (NSSet *)keyPathsForValuesAffectingProbablyADuck { return [NSSet setWithObjects:@”walksLikeADuck”, @”quacksLikeADuck”, nil]; } - (BOOL)isProbablyADuck { return _quacksLikeADuck && _walksLikeADuck; }
10. ReactiveCocoa
11. RAC(self.probablyADuck) = [RACSignal combineLatest:@[ RACAbleWithStart(self.walksLikeADuck), RACAbleWithStart(self.quacksLikeADuck) ] reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quaks.boolValue); }];
13. [self.usernameField addTarget:self action:@selector(textFieldDidUpdate:) forControlEvents:UIControlEventEditingChanged]; [self.emailField addTarget:self action:@selector(textFieldDidUpdate:) forControlEvents:UIControlEventEditingChanged]; - (void)textFieldDidUpdate:(UITextField *)textField { BOOL validUsername = self.usernameField.text.length > 0; BOOL validEmail = [self.emailField.text uik_isEmail]; self.signupButton.enabled = validEmail && validUsername; }
14. because programming
15. [self.usernameField addTarget:self action:@selector(textFieldDidUpdate:) forControlEvents:UIControlEventEditingChanged]; [self.emailField addTarget:self action:@selector(textFieldDidUpdate:) forControlEvents:UIControlEventEditingChanged]; - (void)textFieldDidUpdate:(UITextField *)textField { BOOL validUsername = self.usernameField.text.length > 0; BOOL validEmail = [self.emailField.text uik_isEmail]; self.signupButton.enabled = validEmail && validUsername; }
16. RAC(self.signupButton.enabled) = [RACSignal combineLatest:@[ self.usernameField.rac_textSignal, self.emailField.rac_textSignal ] reduce:^(NSString *username, NSString *email) { BOOL validUsername = username.length > 0; BOOL validEmail = [email uik_isEmail]; return @(validUsername && validEmail); }];
17. FRP
20. ReactiveCocoa
21. @YES @NO @YES RACSignal
22. <UIControlEventEditingChanged> RACSignal
23. {“json_string”: “ohai”} RACSignal
24. RACSignal - (void)sendNext:(id)value; - (void)sendCompleted; - (void)sendError:(NSError *)error;
25. so, what?
26. map, reduce, filter
27. Let’s talk about Asynchrony
29. Blocks are awesome
30. void (^cb)(id operation, id result); void (^cb)(id operation, NSError *error); void (^cb)(id result, NSError *error); void (^cb)(NSError *error, id result);
31. [client logIn:^{ [client loadMeUser:^(UIKUser *user) { [client loadNewslettersForUser:user success:^(NSArray *result) NSLog(@"Your newsletters: %@", array); } failure:^(NSError *error) { // … }]; } failure:^(NSError *error) { // … }]; } failure:^(NSError *error) { // … }];
32. RACSignal
33. - (RACSignal *)logIn; - (RACSignal *)loadMeUser; - (RACSignal *)loadNewslettersForUser:(…)user;
34. [[[[client logIn] sequenceNext:^{ return [client loadMeUser]; }] flattenMap:^(UIKUser *user) { return [client loadNewslettersForUser:user]; }] subscribeNext:^(NSArray *newsletters) { NSLog(@"Your newsletters: %@", newsletters); } error:^(NSError *error) { // … }];
36. - (RACSignal *)validateEmail:(NSString *)email;
37. RACSignal *validEmail = [[self.emailField.rac_textSignal map:^(NSString *email) { return [[client validateEmail:email] startWith:@NO]; }] switchToLatest]; RACSignal *validForm = [RACSignal combineLatest:@[ validUsername, validEmail ] reduce:^(NSNumber *a, NSNumber *b) { return @(a.boolValue && b.boolValue); }]; RAC(self.signupButton.enabled) = validForm;
39. where's the catch?
40. •conceptual overhead •debugging can get tricky (logAll is your friend) •forces you to think
41. should I use it?
42. Probably!
43. state