slides about my talk reactiveCocoa

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;