Brooklyn iOS Developer Meetup February 2014

Transcript

1. 
 robb robb@robb.is ceterum_censeo
2. Let's talk about ReactiveCocoa
3. Let's talk about ReactiveCocoa 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. Start Okay Fail
8. Start Okay Fail power-cycle power-cycle
9. state
10. state
11. duh! " " you say
12. e.g.
13. @property (readwrite) BOOL walks;
 @property (readwrite) BOOL quaks; ! @property (readonly) BOOL duck;
14. duck = walks ∧ quaks
15. 
 
 ! ! - (void)setQuacks:(BOOL)quacks { _quacks = quacks; 
 self.duck = quacks && self.walks;
 } - ( _walks = walks; 
 self.duck = walks }
16. - (BOOL)duck { return self.walks && self.quacks;
 } // duck = walks ∧ quaks
17. ReactiveCocoa
18. Functional Reactive
 Programming
19. Signals instead of variables
20. Pipes, not boxes
21. wtf? " " you may be thinking
22. e.g.
23. RAC(self, duck) = [RACSignal
 combineLatest:@[
 RACObserve(self, walks),
 RACObserve(self, quacks)
 ]]
 reduce:^(NSNumber *walks, NSNumber *quacks) {
 return @(walks.boolValue &&
 quacks.boolValue);
 }];
24. RAC(self, duck) = [RACSignal
 combineLatest:@[
 RACObserve(self, walks),
 RACObserve(self, quacks)
 ]]
 reduce:^(NSNumber *walks, NSNumber *quacks) {
 return @(walks.boolValue &&
 quacks.boolValue);
 }];
25. RAC(self, duck) = [RACSignal
 combineLatest:@[
 RACObserve(self, walks),
 RACObserve(self, quacks)
 ]]
 reduce:^(NSNumber *walks, NSNumber *quacks) {
 return @(walks.boolValue &&
 quacks.boolValue);
 }];
26. RAC(self, duck) = [RACSignal
 combineLatest:@[
 RACObserve(self, walks),
 RACObserve(self, quacks)
 ]]
 reduce:^(NSNumber *walks, NSNumber *quacks) {
 return @(walks.boolValue &&
 quacks.boolValue);
 }];
27. & walks talks duck
28. & walks talks duck
29. & walks talks duck
30. & walks talks duck
31. & walks talks duck
32. RACSignal
33. -(RACDisposable *)subscribe:(id<RACSubscriber>)obj; RACSignal
34. <RACSubscriber>
35. - (void)sendNext:(id)value; <RACSubscriber>
36. - (void)sendNext:(id)value; - (void)sendCompleted; <RACSubscriber>
37. - (void)sendNext:(id)value; - (void)sendCompleted; - (void)sendError:(NSError *)error; <RACSubscriber>
38. so what?
39. Powerful toolset
40. map
41. filter
42. fold
43. write declarative code
44. e.g.
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46. Newsletter Your email address Sign Up robb Brooklyn 4:00 PM 100%
47. Newsletter Sign Up robb robb Brooklyn 4:00 PM 100%
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49. Your name Your email address Sign Up validate Newsletter
50. Your name Your email address Sign Up validate that looks familiar! Newsletter
51. - (void)viewDidLoad {
 [super viewDidLoad];
 [self.username
 addTarget:self
 action:@selector(textFieldTextDidChange:)
 forControlEvents:UIControlEventAllEditingEvents];
 [self.email
 addTarget:self
 action:@selector(textFieldTextDidChange:)
 forControlEvents:UIControlEventAllEditingEvents];
 } help!
52. - (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;
 }
53. - (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;
 }
54. ReactiveCocoa
55. 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);
 }]:
56. 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);
 }]:
57. 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);
 }]:
58. 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);
 }]:
59. Your name Your email address Sign Up validate Newsletter
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63. Let's talk about
    Asynchrony
64. [client logInWithSuccess:^{ [client loadMeUserWithSuccess:^(SPUser *me) { [client loadNewslettersForUser:me withSuccess:^(NSArray *newsletters) { NSLog(@"Help me, " "I'm trapped in callback hell!"); } error:^(NSError *error) { // Handle failure } } error:^(NSError *error) { // Handle failure }];
 } error:^(NSError *error) { // Handle failure }];
65. [client logInWithSuccess:^{ [client loadMeUserWithSuccess:^(SPUser *me) { [client loadNewslettersForUser:me withSuccess:^(NSArray *newsletters) { 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?!
66. Let's fix this
67. 1. HTTP Client
68. @interface SPHTTPClient : AFHTTPClient
 
 - (RACSignal *)enqueueRequest:(NSURLRequest *)req;
 
 @end
69. [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]; }];
70. - (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]; !
71. [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]; }];
72. - (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]; !
73. - (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]; !
74. [self enqueueHTTPRequestOperation:operation]; ! return [RACDisposable disposableWithBlock:^{ [operation cancel]; }]; }]; success:^( [subscriber sendNext:response]; [subscriber sendCompleted]; } failure:^( [subscriber sendError:error]; }];
75. [self enqueueHTTPRequestOperation:operation]; ! return [RACDisposable disposableWithBlock:^{ [operation cancel]; }]; }]; success:^( [subscriber sendNext:response]; [subscriber sendCompleted]; } failure:^( [subscriber sendError:error]; }];
76. 2. API interaction
77. - (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];
 }} }];
 }}
78. - (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];
 }} }];
 }}
79. - (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];
 }} }];
 }}
80. - (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];
 }} }];
 }}
81. - (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!

82. - (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];
 }} }];
 }}
83. - (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];
 }} }];
 }}
84. 3. Putting it together
85. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchNewslettersForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); }}
 error:^(NSError *error) { // Handle error }];
86. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchNewslettersForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); }}
 error:^(NSError *error) { // Handle error }];
87. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchNewslettersForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); }}
 error:^(NSError *error) { // Handle error }];
88. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchNewslettersForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); }}
 error:^(NSError *error) { // Handle error }];
89. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchNewslettersForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); }}
 error:^(NSError *error) { // Handle error }];
90. [[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchNewslettersForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); }}
 error:^(NSError *error) { // Handle error }];
91. UI&IO
92. UI+IO
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94. Your name Your email address Sign Up validate Newsletter
95. Your name Your email address Sign Up validate Newsletter
96. oh boy
97. oh boy, why me?
98. 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);
 }];
99. 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);
 }];
100. RAC(self.signUpButton, enabled) = [RACSignal
 combineLatest:@[
 
 
 ]] 
 
 
 
 validName,
 validEmail reduce:^(NSString *name, NSString *email) {
 NSRange at = [email rangeOfString:@"@"];
 return @(at.location != NSNotFound &&
 name.length > 0);
 }];
101. RAC(self.signUpButton, enabled) = [RACSignal
 combineLatest:@[
 
 
 ]] 
 
 
 
 validName,
 validEmail reduce:^(NSString *name, NSString *email) {
 NSRange at = [email rangeOfString:@"@"];
 return @(at.location != NSNotFound &&
 name.length > 0);
 }];
102. RAC(self.signUpButton, enabled) = [RACSignal
 combineLatest:@[
 
 
 ]] 
 
 
 
 validName,
 validEmail reduce:^(NSNumber *name, NSNumber *email) {
 return @(name.boolValue && email.boolValue);
 }]; }];
 

103. RAC(self.signUpButton, enabled) = [RACSignal combineLatest: 
 
 
 
 validName, validEmail reduce:^(NSNumber *name, NSNumber *email) { RACSignal *validName = [self.name.rac_textSignal map:^(NSString *name) { return @(name.length > 0); }];
 
 switchToLatest];
 

104. RACSignal *validName = [self.name.rac_textSignal map:^(NSString *name) { return }] 
 RACSignal *validEmail = [[self.email.rac_textSignal map:^(NSString *email) { return [[client validateEmail:email] startWith:@NO]; }] switchToLatest];
 

105. RACSignal *validName = [self.name.rac_textSignal map:^(NSString *name) { return }] 
 RACSignal *validEmail = [[self.email.rac_textSignal map:^(NSString *email) { return [[client validateEmail:email] startWith:@NO]; }] switchToLatest];
 

106. RACSignal *validName = [self.name.rac_textSignal map:^(NSString *name) { return }] 
 RACSignal *validEmail = [[self.email.rac_textSignal map:^(NSString *email) { return [[client validateEmail:email] startWith:@NO]; }] switchToLatest];
 

107. Your name Your email address Sign Up validate Newsletter
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109. Newsletter Your email address Sign Up robb Brooklyn 4:00 PM 100%
110. Newsletter Sign Up robb robb@robb.is Brooklyn 4:00 PM 100%
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112. Recap
113. + Declarative code Recap
114. + Declarative code + Easy handling of asynchronous tasks Recap
115. + Declarative code + Easy handling of asynchronous tasks + Great Composition Recap
116. + Declarative code + Easy handling of asynchronous tasks + Great Composition − Conceptual overhead Recap
117. + Declarative code + Easy handling of asynchronous tasks + Great Composition − Conceptual overhead − Debugging can get tricky Recap
118. + Declarative code + Easy handling of asynchronous tasks + Great Composition − Conceptual overhead − Debugging can get tricky Recap (dtrace support)
119. Qs?
120. Thanks!
121. iPhone 5 Sketch Template
 courtesy of
 Denis Rojčyk ! Cloud icon
 curtesy of Dmitry Baranovskiy, from The Noun Project