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robb robb@robb.is ceterum_censeo

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speakerdeck.com/robb/ reactivecocoa-nsspain

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Let's talk about ReactiveCocoa

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Let's talk about ReactiveCocoa state

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evil √

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Have you tried turning it off and on again?

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Have you tried turning it off and on again? Have you tried turning it off and on again?

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Start Okay Fail

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Start Okay Fail power-cycle power-cycle

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state

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state

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duh! " " you say

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e.g.

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@property (readwrite) BOOL walks; @property (readwrite) BOOL quaks; @property (readonly) BOOL duck;

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duck = walks ∧ quaks

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- (void)setWalks:(BOOL)walks { _walks = walks; self.duck = walks && self.quacks; }

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- (void)setWalks:(BOOL)walks { _walks = walks; self.duck = walks && self.quacks; } - (void)setQuacks:(BOOL)quacks { _quacks = quacks; self.duck = quacks && self.walks; }

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- (void)setWalks:(BOOL)walks { _walks = walks; self.duck = walks && self.quacks; } - (void)setQuacks:(BOOL)quacks { _quacks = quacks; self.duck = quacks && self.walks; }

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- (BOOL)duck { return self.walks && self.quacks; }

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- (NSSet *)keyPathsForValuesAffectingDuck { return [NSSet setWithArray:@[ @"walks", @"quacks" ]]; } - (BOOL)duck { return self.walks && self.quacks; }

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- (BOOL)duck { return self.walks && self.quacks; } // duck = walks ∧ quaks

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ReactiveCocoa

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Functional Reactive Programming

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Signals instead of variables

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Pipes, not boxes

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wtf? " " you may be thinking

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e.g.

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RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ] reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:

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RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ] reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:

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RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ] reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:

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RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ] reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:

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RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ] reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:

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// 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); }]:

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& walks talks duck

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& walks talks duck

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& walks talks duck

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& walks talks duck

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& walks talks duck

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RACSignal

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-(RACDisposable * )subscribe:(id )obj; RACSignal

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- (void)sendNext:(id)value;

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- (void)sendNext:(id)value; - (void)sendCompleted;

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- (void)sendNext:(id)value; - (void)sendCompleted; - (void)sendError:(NSError *)error;

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so what?

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Powerful toolset

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map

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filter

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fold

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write declarative code

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e.g.

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Newsletter Your name Your email address Sign Up

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Newsletter Your email address Sign Up robb

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Newsletter Sign Up robb robb

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Newsletter Sign Up robb @robb.is Sign Up robb

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Your name Your email address Sign Up validate that looks familiar! Newsletter

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- (void)viewDidLoad { [super viewDidLoad]; [self.username addTarget:self action:@selector(textFieldTextDidChange:) forControlEvents:UIControlEventAllEditingEvents]; [self.email addTarget:self action:@selector(textFieldTextDidChange:) forControlEvents:UIControlEventAllEditingEvents]; } help!

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- (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; }

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- (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; }

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ReactiveCocoa

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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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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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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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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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Your name Your email address Sign Up validate Newsletter

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Newsletter Your name Your email address Sign Up

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Newsletter Sign Up robb

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Newsletter Sign Up robb robb@robb.is Sign Up

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Let's talk about

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Let's talk about Asynchrony

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[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?!

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Let's fix this

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1. HTTP Client

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@interface SPHTTPClient : AFHTTPClient - (RACSignal *)enqueueRequest:(NSURLRequest *)req; @end

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[self enqueueHTTPRequestOperation:operation]; - (RACSignal *)enqueueRequest:(NSURLRequest *)req { return [RACSignal createSignal:^(id 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]; }];

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[self enqueueHTTPRequestOperation:operation]; - (RACSignal *)enqueueRequest:(NSURLRequest *)req { return [RACSignal createSignal:^(id 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]; }];

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- (RACSignal *)enqueueRequest:(NSURLRequest *)req { return [RACSignal createSignal:^(id 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];

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- (RACSignal *)enqueueRequest:(NSURLRequest *)req { return [RACSignal createSignal:^(id 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];

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- (RACSignal *)enqueueRequest:(NSURLRequest *)req { return [RACSignal createSignal:^(id 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];

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[self enqueueHTTPRequestOperation:operation]; return [RACDisposable disposableWithBlock:^{ [operation cancel]; }]; }]; createSignal:^(id 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]; }];

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[self enqueueHTTPRequestOperation:operation]; return [RACDisposable disposableWithBlock:^{ [operation cancel]; }]; }]; createSignal:^(id 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]; }];

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2. API interaction

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- (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]; } }]; }

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- (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]; } }]; }

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- (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]; } }]; }

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- (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]; } }]; }

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- (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!

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- (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]; } }]; }

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- (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]; } }]; }

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3. Putting it together

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[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];

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[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];

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[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];

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[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];

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[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];

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[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];

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[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) { return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];

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UI&IO

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UI+IO

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Your name Your email address Sign Up Newsletter

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Your name Your email address Sign Up validate Newsletter

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Your name Your email address Sign Up validate Newsletter

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, why me? oh boy

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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:@[ ]

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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:@[ ]

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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:@[ ]

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reduce:^(NSString *name, NSString *email) { NSRange at = [email rangeOfString:@"@"]; return @(at.location != NSNotFound && name.length > 0); }]; validName, validEmail RAC(self.signUpButton, enabled) = [RACSignal combineLatest:@[ ]

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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:@[ ]

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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];

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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];

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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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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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Your name Your email address Sign Up validate Newsletter

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Newsletter Your name Your email address Sign Up

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Newsletter Sign Up robb

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Newsletter Sign Up robb robb@robb.is

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Newsletter Sign Up robb robb@robb.is Sign Up

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Recap

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Recap + Declarative code

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Recap + Declarative code + Easy handling of asynchronous tasks

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Recap + Declarative code + Easy handling of asynchronous tasks + Great Composition

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Recap + Declarative code + Easy handling of asynchronous tasks + Great Composition − Conceptual overhead

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Recap + Declarative code + Easy handling of asynchronous tasks + Great Composition − Conceptual overhead − Debugging can get tricky

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Recap (dtrace support coming soon) + Declarative code + Easy handling of asynchronous tasks + Great Composition − Conceptual overhead − Debugging can get tricky

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Qs?

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Thanks!

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iPhone 5 Setch Template courtesy of Denis Rojčyk Cloud icon curtesy of Dmitry Baranovskiy, from The Noun Project