ReactiveCocoa NSSpain

My talk for NSSpain 2013 on ReactiveCocoa

1. robb robb@robb.is ceterum_censeo
2. speakerdeck.com/robb/ reactivecocoa-nsspain
3. Let's talk about ReactiveCocoa
4. Let's talk about ReactiveCocoa state
5. evil √
6. Have you tried turning it off and on again?
7. Have you tried turning it off and on again? Have you tried turning it off and on again?
8. Start Okay Fail
9. Start Okay Fail power-cycle power-cycle
10. state
11. state
12. duh! " " you say
13. e.g.
14. @property (readwrite) BOOL walks; @property (readwrite) BOOL quaks; @property (readonly) BOOL duck;
15. duck = walks ∧ quaks
16. - (void)setWalks:(BOOL)walks { _walks = walks; self.duck = walks && self.quacks; }
17. - (void)setWalks:(BOOL)walks { _walks = walks; self.duck = walks && self.quacks; } - (void)setQuacks:(BOOL)quacks { _quacks = quacks; self.duck = quacks && self.walks; }
18. - (void)setWalks:(BOOL)walks { _walks = walks; self.duck = walks && self.quacks; } - (void)setQuacks:(BOOL)quacks { _quacks = quacks; self.duck = quacks && self.walks; }
19. - (BOOL)duck { return self.walks && self.quacks; }
20. - (NSSet *)keyPathsForValuesAffectingDuck { return [NSSet setWithArray:@[ @"walks", @"quacks" ]]; } - (BOOL)duck { return self.walks && self.quacks; }
21. - (BOOL)duck { return self.walks && self.quacks; } // duck = walks ∧ quaks
22. ReactiveCocoa
23. Functional Reactive Programming
24. Signals instead of variables
25. Pipes, not boxes
26. wtf? " " you may be thinking
27. e.g.
28. RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ] reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:
29. RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ] reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:
30. RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ] reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:
31. RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ] reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:
32. RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ] reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:
33. // and it even does KVO! RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ] reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:
34. & walks talks duck
35. & walks talks duck
36. & walks talks duck
37. & walks talks duck
38. & walks talks duck
39. RACSignal
40. -(RACDisposable * )subscribe:(id<RACSubscriber> )obj; RACSignal
41. <RACSubscriber>
42. - (void)sendNext:(id)value; <RACSubscriber>
43. - (void)sendNext:(id)value; - (void)sendCompleted; <RACSubscriber>
44. - (void)sendNext:(id)value; - (void)sendCompleted; - (void)sendError:(NSError *)error; <RACSubscriber>
45. so what?
46. Powerful toolset
47. map
48. filter
49. fold
50. write declarative code
51. e.g.
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58. - (void)viewDidLoad { [super viewDidLoad]; [self.username addTarget:self action:@selector(textFieldTextDidChange:) forControlEvents:UIControlEventAllEditingEvents]; [self.email addTarget:self action:@selector(textFieldTextDidChange:) forControlEvents:UIControlEventAllEditingEvents]; } help!
59. - (void)textFieldTextDidChange:(UITextField *)field { BOOL validUsername = self.username.text.length > 0; NSRange at = [self.email.text rangeOfString:@"@"]; BOOL validEmail = at.location != NSNotFound; self.signupButton.enabled = validUsername && validEmail; }
60. - (void)textFieldTextDidChange:(UITextField *)field { BOOL validUsername = self.username.text.length > 0; NSRange at = [self.email.text rangeOfString:@"@"]; BOOL validEmail = at.location != NSNotFound; self.signupButton.enabled = validUsername && validEmail; }
61. ReactiveCocoa
62. RAC(self.signUpButton, enabled) = [RACSignal combineLatest:@[ self.name.rac_textSignal self.email.rac_textSignal ] reduce:^(NSString *name, NSString *email) { NSRange at = [email rangeOfString:@"@"]; return @(at.location != NSNotFound && name.length > 0); }]:
63. RAC(self.signUpButton, enabled) = [RACSignal combineLatest:@[ self.name.rac_textSignal self.email.rac_textSignal ] reduce:^(NSString *name, NSString *email) { NSRange at = [email rangeOfString:@"@"]; return @(at.location != NSNotFound && name.length > 0); }]:
64. RAC(self.signUpButton, enabled) = [RACSignal combineLatest:@[ self.name.rac_textSignal self.email.rac_textSignal ] reduce:^(NSString *name, NSString *email) { NSRange at = [email rangeOfString:@"@"]; return @(at.location != NSNotFound && name.length > 0); }]:
65. RAC(self.signUpButton, enabled) = [RACSignal combineLatest:@[ self.name.rac_textSignal self.email.rac_textSignal ] reduce:^(NSString *name, NSString *email) { NSRange at = [email rangeOfString:@"@"]; return @(at.location != NSNotFound && name.length > 0); }]:
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70. Let's talk about
71. Let's talk about Asynchrony
72. [client logInWithSuccess:^{ [client loadMeUserWithSuccess:^(SPUser *me) { [client loadFilesForUser:me withSuccess:^(NSArray *files) { NSLog(@"Help me, " "I'm trapped in callback hell!"); } error:^(NSError *error) { // Handle failure } } error:^(NSError *error) { // Handle failure }]; } error:^(NSError *error) { // Handle failure }]; omg, why?!
73. Let's fix this
74. 1. HTTP Client
75. @interface SPHTTPClient : AFHTTPClient - (RACSignal *)enqueueRequest:(NSURLRequest *)req; @end
76. [self enqueueHTTPRequestOperation:operation]; - (RACSignal *)enqueueRequest:(NSURLRequest *)req { return [RACSignal createSignal:^(id<RACSubscriber> subscriber) { AFHTTPRequestOperation *operation; operation = [self HTTPRequestOperationWithRequest:req success:^(id operation, id response) { [subscriber sendNext:response]; [subscriber sendCompleted]; } failure:^(id operation, NSError *error) { [subscriber sendError:error]; }];
77. [self enqueueHTTPRequestOperation:operation]; - (RACSignal *)enqueueRequest:(NSURLRequest *)req { return [RACSignal createSignal:^(id<RACSubscriber> subscriber) { AFHTTPRequestOperation *operation; operation = [self HTTPRequestOperationWithRequest:req success:^(id operation, id response) { [subscriber sendNext:response]; [subscriber sendCompleted]; } failure:^(id operation, NSError *error) { [subscriber sendError:error]; }];
78. - (RACSignal *)enqueueRequest:(NSURLRequest *)req { return [RACSignal createSignal:^(id<RACSubscriber> subscriber) { AFHTTPRequestOperation *operation; operation = [self HTTPRequestOperationWithRequest:req success:^(id operation, id response) { [subscriber sendNext:response]; [subscriber sendCompleted]; } failure:^(id operation, NSError *error) { [subscriber sendError:error]; }]; [self enqueueHTTPRequestOperation:operation];
79. - (RACSignal *)enqueueRequest:(NSURLRequest *)req { return [RACSignal createSignal:^(id<RACSubscriber> subscriber) { AFHTTPRequestOperation *operation; operation = [self HTTPRequestOperationWithRequest:req success:^(id operation, id response) { [subscriber sendNext:response]; [subscriber sendCompleted]; } failure:^(id operation, NSError *error) { [subscriber sendError:error]; }]; [self enqueueHTTPRequestOperation:operation];
80. - (RACSignal *)enqueueRequest:(NSURLRequest *)req { return [RACSignal createSignal:^(id<RACSubscriber> subscriber) { AFHTTPRequestOperation *operation; operation = [self HTTPRequestOperationWithRequest:req success:^(id operation, id response) { [subscriber sendNext:response]; [subscriber sendCompleted]; } failure:^(id operation, NSError *error) { [subscriber sendError:error]; }]; [self enqueueHTTPRequestOperation:operation];
81. [self enqueueHTTPRequestOperation:operation]; return [RACDisposable disposableWithBlock:^{ [operation cancel]; }]; }]; createSignal:^(id<RACSubscriber> subscriber) { AFHTTPRequestOperation *operation; operation = [self HTTPRequestOperationWithRequest:req success:^(id operation, id response) { [subscriber sendNext:response]; [subscriber sendCompleted]; } failure:^(id operation, NSError *error) { [subscriber sendError:error]; }];
82. [self enqueueHTTPRequestOperation:operation]; return [RACDisposable disposableWithBlock:^{ [operation cancel]; }]; }]; createSignal:^(id<RACSubscriber> subscriber) { AFHTTPRequestOperation *operation; operation = [self HTTPRequestOperationWithRequest:req success:^(id operation, id response) { [subscriber sendNext:response]; [subscriber sendCompleted]; } failure:^(id operation, NSError *error) { [subscriber sendError:error]; }];
83. 2. API interaction
84. - (RACSignal *)fetchMeUser return [[self.client getPath:@"/me"] flattenMap:^(id JSON) { NSError *error; SPUser *user = [SPUser userWithJSON:JSON error:&error]; if (user == nil) { return [RACSignal error:error]; } else { return [RACSignal return:user]; } }]; }
85. - (RACSignal *)fetchMeUser return [[self.client getPath:@"/me"] flattenMap:^(id JSON) { NSError *error; SPUser *user = [SPUser userWithJSON:JSON error:&error]; if (user == nil) { return [RACSignal error:error]; } else { return [RACSignal return:user]; } }]; }
86. - (RACSignal *)fetchMeUser return [[self.client getPath:@"/me"] flattenMap:^(id JSON) { NSError *error; SPUser *user = [SPUser userWithJSON:JSON error:&error]; if (user == nil) { return [RACSignal error:error]; } else { return [RACSignal return:user]; } }]; }
87. - (RACSignal *)fetchMeUser return [[self.client getPath:@"/me"] flattenMap:^(id JSON) { NSError *error; SPUser *user = [SPUser userWithJSON:JSON error:&error]; if (user == nil) { return [RACSignal error:error]; } else { return [RACSignal return:user]; } }]; }
88. - (RACSignal *)fetchMeUser return [[self.client getPath:@"/me"] flattenMap:^(id JSON) { NSError *error; SPUser *user = [SPUser userWithJSON:JSON error:&error]; if (user == nil) { return [RACSignal error:error]; } else { return [RACSignal return:user]; } }]; } check out Mantle!
89. - (RACSignal *)fetchMeUser return [[self.client getPath:@"/me"] flattenMap:^(id JSON) { NSError *error; SPUser *user = [SPUser userWithJSON:JSON error:&error]; if (user == nil) { return [RACSignal error:error]; } else { return [RACSignal return:user]; } }]; }
90. - (RACSignal *)fetchMeUser return [[self.client getPath:@"/me"] flattenMap:^(id JSON) { NSError *error; SPUser *user = [SPUser userWithJSON:JSON error:&error]; if (user == nil) { return [RACSignal error:error]; } else { return [RACSignal return:user]; } }]; }
91. 3. Putting it together
92. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
93. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
94. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
95. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
96. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
97. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
98. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
99. UI&IO
100. UI+IO
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104. , why me? oh boy
105. self.name.rac_textSignal self.email.rac_textSignal reduce:^(NSString *name, NSString *email) { NSRange at = [email rangeOfString:@"@"]; return @(at.location != NSNotFound && name.length > 0); }]; RAC(self.signUpButton, enabled) = [RACSignal combineLatest:@[ ]
106. self.name.rac_textSignal self.email.rac_textSignal reduce:^(NSString *name, NSString *email) { NSRange at = [email rangeOfString:@"@"]; return @(at.location != NSNotFound && name.length > 0); }]; RAC(self.signUpButton, enabled) = [RACSignal combineLatest:@[ ]
107. validName, validEmail reduce:^(NSString *name, NSString *email) { NSRange at = [email rangeOfString:@"@"]; return @(at.location != NSNotFound && name.length > 0); }]; reduce:^(NSString *name, NSString *email) { NSRange at = [email rangeOfString:@"@"]; return @(at.location != NSNotFound && name.length > 0); }]; RAC(self.signUpButton, enabled) = [RACSignal combineLatest:@[ ]
108. reduce:^(NSString *name, NSString *email) { NSRange at = [email rangeOfString:@"@"]; return @(at.location != NSNotFound && name.length > 0); }]; validName, validEmail RAC(self.signUpButton, enabled) = [RACSignal combineLatest:@[ ]
109. reduce:^(NSNumber *name, NSNumber *email) { return @(name.boolValue && email.boolValue); }]; validName, validEmail map:^(NSString *name) { return @(name.length > 0); }]; RAC(self.signUpButton, enabled) = [RACSignal combineLatest:@[ ]
110. RACSignal *validName = [self.name.rac_textSignal map:^(NSString *name) { return @(name.length > 0); }]; reduce:^(NSNumber *name, NSNumber *email) { validName, validEmail RAC(self.signUpButton, enabled) = [RACSignal combineLatest:@[ ] RACSignal *validEmail = [[self.email.rac_textSignal map:^(NSString *email) { return [[client validateEmail:email] startWith:@NO]; }] switchToLatest];
111. RACSignal *validName = [self.name.rac_textSignal map:^(NSString *name) { return @(name.length > 0); }]; RACSignal *validEmail = [[self.email.rac_textSignal map:^(NSString *email) { return [[client validateEmail:email] startWith:@NO]; }] switchToLatest];
112. RACSignal *validEmail = [[self.email.rac_textSignal map:^(NSString *email) { return [[client validateEmail:email] startWith:@NO]; }] switchToLatest]; RACSignal *validName = [self.name.rac_textSignal map:^(NSString *name) { return @(name.length > 0); }];
113. RACSignal *validEmail = [[self.email.rac_textSignal map:^(NSString *email) { return [[client validateEmail:email] startWith:@NO]; }] switchToLatest]; RACSignal *validName = [self.name.rac_textSignal map:^(NSString *name) { return @(name.length > 0); }];
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119. Recap
120. Recap + Declarative code
121. Recap + Declarative code + Easy handling of asynchronous tasks
122. Recap + Declarative code + Easy handling of asynchronous tasks + Great Composition
123. Recap + Declarative code + Easy handling of asynchronous tasks + Great Composition − Conceptual overhead
124. Recap + Declarative code + Easy handling of asynchronous tasks + Great Composition − Conceptual overhead − Debugging can get tricky
125. Recap (dtrace support coming soon) + Declarative code + Easy handling of asynchronous tasks + Great Composition − Conceptual overhead − Debugging can get tricky
126. Qs?
127. Thanks!
128. iPhone 5 Setch Template courtesy of Denis Rojčyk Cloud icon curtesy of Dmitry Baranovskiy, from The Noun Project