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ReactiveCocoa
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Robert Böhnke
May 02, 2013
Programming
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2.7k
ReactiveCocoa
My talk for UIKonf 2013 about ReactiveCocoa and how to get rid of state
Robert Böhnke
May 02, 2013
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Transcript
ReactiveCocoa OR: How I stopped worrying about state and love
FRP
✉ robb robb@robb.is tmp ceterum_censeo
Let’s talk about 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?
state
@property (readwrite, …) BOOL quacksLikeADuck; @property (readwrite, …) BOOL walksLikeADuck;
@property (readonly, …) BOOL probablyADuck;
+ (NSSet *)keyPathsForValuesAffectingProbablyADuck { return [NSSet setWithObjects:@”walksLikeADuck”, @”quacksLikeADuck”, nil]; }
- (BOOL)isProbablyADuck { return _quacksLikeADuck && _walksLikeADuck; }
ReactiveCocoa
RAC(self.probablyADuck) = [RACSignal combineLatest:@[ RACAbleWithStart(self.walksLikeADuck), RACAbleWithStart(self.quacksLikeADuck) ] reduce:^(NSNumber *walks, NSNumber
*quacks) { return @(walks.boolValue && quaks.boolValue); }];
None
[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; }
because programming
[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; }
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); }];
FRP
None
None
ReactiveCocoa
@YES @NO @YES RACSignal
<UIControlEventEditingChanged> RACSignal
{“json_string”: “ohai”} RACSignal
RACSignal - (void)sendNext:(id)value; - (void)sendCompleted; - (void)sendError:(NSError *)error;
so, what?
map, reduce, filter
Let’s talk about Asynchrony
None
Blocks are awesome
void (^cb)(id operation, id result); void (^cb)(id operation, NSError *error);
void (^cb)(id result, NSError *error); void (^cb)(NSError *error, id result);
[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) { // … }];
RACSignal
- (RACSignal *)logIn; - (RACSignal *)loadMeUser; - (RACSignal *)loadNewslettersForUser:(…)user;
[[[[client logIn] sequenceNext:^{ return [client loadMeUser]; }] flattenMap:^(UIKUser *user) {
return [client loadNewslettersForUser:user]; }] subscribeNext:^(NSArray *newsletters) { NSLog(@"Your newsletters: %@", newsletters); } error:^(NSError *error) { // … }];
None
- (RACSignal *)validateEmail:(NSString *)email;
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;
None
where's the catch?
•conceptual overhead •debugging can get tricky (logAll is your friend)
•forces you to think
should I use it?
Probably!
state
None