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ReactiveCocoa NSSpain
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Robert Böhnke
September 18, 2013
Programming
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ReactiveCocoa NSSpain
My talk for NSSpain 2013 on ReactiveCocoa
Robert Böhnke
September 18, 2013
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Transcript
robb robb@robb.is ceterum_censeo
speakerdeck.com/robb/ reactivecocoa-nsspain
Let's talk about ReactiveCocoa
Let's talk about ReactiveCocoa state
evil √
Have you tried turning it off and on again?
Have you tried turning it off and on again? Have
you tried turning it off and on again?
Start Okay Fail
Start Okay Fail power-cycle power-cycle
state
state
duh! " " you say
e.g.
@property (readwrite) BOOL walks; @property (readwrite) BOOL quaks; @property (readonly)
BOOL duck;
duck = walks ∧ quaks
- (void)setWalks:(BOOL)walks { _walks = walks; self.duck = walks &&
self.quacks; }
- (void)setWalks:(BOOL)walks { _walks = walks; self.duck = walks &&
self.quacks; } - (void)setQuacks:(BOOL)quacks { _quacks = quacks; self.duck = quacks && self.walks; }
- (void)setWalks:(BOOL)walks { _walks = walks; self.duck = walks &&
self.quacks; } - (void)setQuacks:(BOOL)quacks { _quacks = quacks; self.duck = quacks && self.walks; }
- (BOOL)duck { return self.walks && self.quacks; }
- (NSSet *)keyPathsForValuesAffectingDuck { return [NSSet setWithArray:@[ @"walks", @"quacks" ]];
} - (BOOL)duck { return self.walks && self.quacks; }
- (BOOL)duck { return self.walks && self.quacks; } // duck
= walks ∧ quaks
ReactiveCocoa
Functional Reactive Programming
Signals instead of variables
Pipes, not boxes
wtf? " " you may be thinking
e.g.
RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ]
reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:
RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ]
reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:
RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ]
reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:
RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ]
reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:
RAC(self, duck) = [RACSignal combineLatest:@[ RACObserve(self, walks), RACObserve(self, quacks) ]
reduce:^(NSNumber *walks, NSNumber *quacks) { return @(walks.boolValue && quacks.boolValue); }]:
// 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); }]:
& walks talks duck
& walks talks duck
& walks talks duck
& walks talks duck
& walks talks duck
RACSignal
-(RACDisposable * )subscribe:(id<RACSubscriber> )obj; RACSignal
<RACSubscriber>
- (void)sendNext:(id)value; <RACSubscriber>
- (void)sendNext:(id)value; - (void)sendCompleted; <RACSubscriber>
- (void)sendNext:(id)value; - (void)sendCompleted; - (void)sendError:(NSError *)error; <RACSubscriber>
so what?
Powerful toolset
map
filter
fold
write declarative code
e.g.
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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!
- (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; }
- (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; }
ReactiveCocoa
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); }]:
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); }]:
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); }]:
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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Let's talk about
Let's talk about Asynchrony
[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?!
Let's fix this
1. HTTP Client
@interface SPHTTPClient : AFHTTPClient - (RACSignal *)enqueueRequest:(NSURLRequest *)req; @end
[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]; }];
[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]; }];
- (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];
- (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];
- (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];
[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]; }];
[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]; }];
2. API interaction
- (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]; } }]; }
- (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]; } }]; }
- (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]; } }]; }
- (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]; } }]; }
- (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!
- (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]; } }]; }
- (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]; } }]; }
3. Putting it together
[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) {
return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) {
return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) {
return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) {
return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) {
return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) {
return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
[[[[client logIn] then:^{ return [client fetchMeUser]; }] flattenMap:^(SPUser *me) {
return [client fetchFilesForUser:me]; }] subscribeNext:^(NSArray *files) { NSLog(@"Files: %@", files); } error:^(NSError *error) { // Handle error }];
UI&IO
UI+IO
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, why me? oh boy
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:@[ ]
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:@[ ]
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:@[ ]
reduce:^(NSString *name, NSString *email) { NSRange at = [email rangeOfString:@"@"];
return @(at.location != NSNotFound && name.length > 0); }]; validName, validEmail RAC(self.signUpButton, enabled) = [RACSignal combineLatest:@[ ]
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:@[ ]
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];
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];
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); }];
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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Recap
Recap + Declarative code
Recap + Declarative code + Easy handling of asynchronous tasks
Recap + Declarative code + Easy handling of asynchronous tasks
+ Great Composition
Recap + Declarative code + Easy handling of asynchronous tasks
+ Great Composition − Conceptual overhead
Recap + Declarative code + Easy handling of asynchronous tasks
+ Great Composition − Conceptual overhead − Debugging can get tricky
Recap (dtrace support coming soon) + Declarative code + Easy
handling of asynchronous tasks + Great Composition − Conceptual overhead − Debugging can get tricky
Qs?
Thanks!
iPhone 5 Setch Template courtesy of Denis Rojčyk Cloud icon
curtesy of Dmitry Baranovskiy, from The Noun Project