This document summarizes the ReactiveCocoa framework. It describes the differences between imperative and declarative programming. ReactiveCocoa uses a declarative and functional approach. It introduces key classes like RACSignal, RACStream, RACCommand, and RACSubject. It provides examples of how to use these classes to reactively bind UI elements together, handle events, and manipulate signals.

1. ReactiveCocoa
@iacisclo

2. Programación imperativa.
• Describe detalladamente los
pasos a seguir.
• Continuos cambios de
estado.
• El orden de ejecución es vital.
• Muchos condicionales.

3. Programación declarativa
• Tu describes directamente los
resultados.
• El orden de ejecución no
importa.
• Sin apenas condicionales.
• No hay que estar pendiente
del estado.

4. ReactiveCocoa
• Compatible desde iOS 5.0+ y OS X 10.7+.
• Versión actual 2.2.4.
• Combina declarativa y funcional.
• Compatible con código no RAC.

5. ¿Como?
NSString *name = @"Belén";
NSString *surname = @“_Esteban”;
NSString *completeName = [name stringByAppendingString:surname];
surname = @“_Esteban, háztelo mirar”;
NSLog(@"%@",completeName);
El resultado sería “Belén_Esteban” pero con programación reactiva
sería “Belén_Esteban, háztelo mirar”.

6. [self.textField.rac_textSignal subscribeNext:^(NSString *value) {
self.lblValue.text = value;
}];

7. // Imperative
!
for (NSString *device in devices)
if ([device isEqualToString:@"iPod"]) {
self.name = device;
}
}
!
// Reactive
RAC(self, name) = [devices.rac_sequence.signal filter:^BOOL(NSString *device) {
return [device isEqualToString:@"iPod"];
}];

8. Clases
• RACStream
• RACSignal
• RACSubscriber
• RACSubject
• RACCommand
• RACMulticastConnection
• RACSequence
• RACDisposable
• RACSheduler

9. RACStream
• El padre de Todos.
• Es un conjunto de valores.
• Las señales contienen RACStreams.
• Los valores se recuperan de forma secuencial.

10. RACCommand
• Crea y se subscribe a una señal, generalmente
iniciada por UI.
self.button.rac_command = [[RACCommand alloc] initWithSignalBlock:^(id _) {
self.lblValue.text = @"Button tapped";
return [RACSignal empty];
}];
RACCommand *createAccount = [[RACCommand alloc]initWithEnabled:formValid signalBlock:^RACSignal *(id input) {
BOOL success = [IACClient logggin];
return [RACSignal return:@(success)];
}];
!
self.createButton.rac_command = createAccount;

11. RACSignal
• Envian 3 tipos de eventos: NEXT, ERROR, COMPLETED.
[signal subscribeNext:^(id x) {
NSLog(@"en la subscripción");
} error:^(NSError *error) {
NSLog(@"ha ocurrido un error.");
} completed:^{
NSLog(@"señal completa");
}];

12. RACSignal
RACSignal *executing = [racCommand.executing deliverOn:RACScheduler.mainThreadScheduler];
!
RACSignal *fieldTextColor = [executing map:^(NSNumber *x) {
return x.boolValue ? [UIColor lightGrayColor] : [UIColor blackColor];
}];
RACSignal *signal = @[@"iPhone",@"iPad",@"iMac",@"iPod"].rac_sequence.signal;
[[signal filter:^BOOL(NSString *value) {
return [value isEqualToString:@"iPad"];
}]subscribeNext:^(NSString *filterValue) {
self.lblValue.text = filterValue;
}];

13. RACSignal
!
RACSignal *formValid = [RACSignal
combineLatest:@[
self.firstNameField.rac_textSignal,
self.lastNameField.rac_textSignal,
self.emailField.rac_textSignal,
]
reduce:^(NSString *firstName,
NSString *lastName,
NSString *email){
return @(firstName.length > 0 &&
lastName.length > 0 &&
email.length > 0);
}];

14. RACSubject
• Señal que se puede controlar.
RACSubject *letters = [RACSubject subject];
[letters subscribeNext:^(NSString *letter) {
NSLog(@"%@",letter);
} completed:^{
NSLog(@"complete");
}];
[letters sendNext:@"A"];
[letters sendNext:@"B"];
[letters sendCompleted];

15. rac_liftSelector:withSignals:
!
self.delegate = [RACSubject subject];
!
[self.navigationController rac_liftSelector:@selector(pushViewController:animated:)
withSignals:self.delegate,[RACSignal return:@YES], nil];
!
/////
!
IACDetailViewController *detailVC = [self.storyboard
instantiateViewControllerWithIdentifier:@"IACDetailViewController"];
!
[self.delegate sendNext:detailVC];
!

16. RACSubscriber
• Todo objeto que espera o es capaz de
subscribirse a una señal
[[self saveImage:[UIImage imageNamed:@"image1"] withName:@"image1"]then:^RACSignal *{
NSLog(@"image guardada correctamente");
return nil;
}];
!
/////////
!
-(RACSignal *)saveImage:(UIImage *)image withName:(NSString *)name{
return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *savedImagePath = [documentsDirectory stringByAppendingPathComponent:@"savedImage.png"];
NSData *imageData = UIImagePNGRepresentation(image);
BOOL error = [imageData writeToFile:savedImagePath atomically:NO];
if (error) {
[subscriber sendError:nil];
}else{
[subscriber sendCompleted];
}
return nil;
}];
}

17. RACSequence
• Colecciones, señales guiadas.
RACSequence *devices = @[@"iPhone",@"iPad",@"iPod"].rac_sequence;
RACSequence *computers = @[@"iMac",@"Mac Mini",@"Macbook Air",@"Macbook
Pro"].rac_sequence;
RACSequence *concatenated = [devices concat:computers];
[concatenated.signal subscribeNext:^(id x) {
NSLog(@"%@",x);
}];

18. RACSequence
• Colecciones, señales guiadas.
RACSignal *devices = @[@"iPhone",@"iPad",@"iPod"].rac_sequence.signal;
RACSignal *sequenced = [[devices
doNext:^(NSString *device) {
NSLog(@"trabajamos con el objeto %@", device);
}]
then:^{
return @[@"iMac",@"Mac Mini",@"Macbook
Air",@"Macbook Pro"].rac_sequence.signal;
}];
[sequenced subscribeNext:^(NSString *computer) {
NSLog(@"%@",computer);
}];

19. do…
RACSignal *sequenced = [[[[devices
doNext:^(NSString *device) {
!
NSLog(@“antes de la subscripción %@“,device);
!
}]doError:^(NSError *error) {
!
NSLog(@"antes del error: %@", error);
!
}]doCompleted:^{
!
NSLog(@"señal antes de ser completada”);
!
}]then:^{
!
NSLog(@"señal ya completada”);
!
}];

20. RACDisposable
• Baja o limpieza de señales.
RACDisposable *subscription =
[self.textField.rac_textSignal
subscribeNext:^(NSString *text) {
self.lblValue.text = text;
}];
// en un futuro;
[subscription dispose];

21. Delegados
• Podemos sustituir delegados facilmente
self.textView.delegate = self;
[[self rac_signalForSelector:@selector(textViewDidChange:)fromProtocol:
@protocol(UITextViewDelegate)]subscribeNext:^(RACTuple *arguments) {
UITextView *textview = arguments.first;
}];
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:@"Alert"
message:@"message"
delegate:self
cancelButtonTitle:@"cancel"
otherButtonTitles:@"ok", nil];
[alert show];
[alert.rac_buttonClickedSignal subscribeNext:^(NSNumber *index) {
NSLog(@"%@",index);
}];

22. Eventos de control
• UIControlEvetTouchDown
• UIControlEventTouchDownRepeat
• UIControlEventTouchDragInside
• UIControlEventTouchDragOutside
• UIControlEventTouchDragEnter
• UIControlEventTouchDragExit
• UIControlEventTouchUpInside
• UIControlEventTouchUpOutside
• UIControlEventTouchCancel
• UIControlEventValueChanged
• UIControlEventEditingDidBegin
• UIControlEventEditingChanged
• UIControlEventEditingDidEnd
• UIControlEventEditingDidEndOnExit
• UIControlEventAllTouchEvents
• UIControlEventAllEditingEvents
• UIControlEventApplicationReserved
• UIControlEventSystemReserved

23. Eventos de control
[[stepper rac_signalForControlEvents:UIControlEventAllTouchEvents]
subscribeNext:^(UIStepper *stepper) {
self.lblValue.text = [NSString stringWithFormat:@"%f",stepper.value];
}];
RAC(self.textField, textColor) = [[self.textField rac_signalForControlEvents:
UIControlEventAllEvents]map:^id(UITextField *textfield) {
if (textfield.text.length >3) {
return [UIColor blackColor];
}else{
return [UIColor redColor];
}
}];

24. RACSheduler
• GCD en RAC.
[[self.textField.rac_textSignal deliverOn:[RACScheduler mainThreadScheduler]]
subscribeNext:^(NSString *value) {
self.lblValue.text = value;
}];
RACScheduler *scheduler = [RACScheduler
schedulerWithPriority:RACSchedulerPriorityBackground];
[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
return nil;
}]subscribeOn:scheduler];

25. RACSheduler
//////
!
[[[self signalForLoadingImage:tweet.profileImageUrl]
deliverOn:[RACScheduler mainThreadScheduler]]
subscribeNext:^(UIImage *image) {
cell.twitterAvatarView.image = image;
}];
!
///////
!
-(RACSignal *)signalForLoadingImage:(NSString *)imageUrl {
RACScheduler *scheduler = [RACScheduler
schedulerWithPriority:RACSchedulerPriorityBackground];
return [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber)
{
NSData *data = [NSData dataWithContentsOfURL:[NSURL
URLWithString:imageUrl]];
UIImage *image = [UIImage imageWithData:data];
[subscriber sendNext:image];
[subscriber sendCompleted];
return nil;
}]subscribeOn:scheduler];
}

26. Memoria
__weak ViewController *bself = self;
[[self.searchText.rac_textSignal
map:^id(NSString *text) {
return [self isValidSearchText:text] ?
[UIColor whiteColor] : [UIColor yellowColor];
}]
subscribeNext:^(UIColor *color) {
bself.searchText.backgroundColor = color;
}];

27. Memoria
#import "RACEXTScope.h"
!
!
@weakify(self)
[[self.searchText.rac_textSignal
map:^id(NSString *text) {
return [self isValidSearchText:text] ?
[UIColor whiteColor] : [UIColor yellowColor];
}]
subscribeNext:^(UIColor *color) {
@strongify(self)
self.searchText.backgroundColor = color;
}];

28. RACObserve(TARGET, KEYPATH)
@weakify(self)
[RACObserve(self, modelArray) subscribeNext:^(id x) {
@strongify(self)
[self.collectionView reloadData];
}];
[[[RACObserve(photoModel, imageData)filter:^BOOL(id value) {
return value != nil;
}]map:^id(id value) {
return [UIImage imageWithData:value];
}]setKeyPath:@keypath(self.imageView, image)
onObject:self.imageView];

29. RAC(TARGET, …)
RAC(self,dateAdded) = [RACObserve(self.model,dateAdded)map:^(NSDate*date){
return [[ViewModel dateFormatter] stringFromDate:date];
}];
!
RAC(self, name) = self.textField.rac_textSignal;

30. return;