RxSwift

# RxSwift

----

Asynchronous Events in Cocoa
* Target-Action
* NSNotificationCenter
* Key-Value Observing
* Delegates
* Callback Closures

---

### One ring to rule them all(sequences)
`Observable<Element>`

---

### Sequence event type
```
enum Event<Element>  {
    case Next(Element)
    case Error(ErrorType)
    case Completed
}                       
```

---

### Creating a sequence
```
let o = Observable.create { observer in 
        observer.on(.Next("Hello world!"))
        observer.on(.Completed)
    return NopDisposable.instance
}
```

---

### Subscribe
```
protocol ObservableType {
    func subscribe(on: (event: Event) -> Void) -> Disposable
    func subscribe(
        onNext: ((Self.E) -> Swift.Void)? = default,
        onError: ((Error) -> Swift.Void)? = default,
        onCompleted: (() -> Swift.Void)? = default,
        onDisposed: (() -> Swift.Void)? = default) -> Disposable
}
```

---

### Observable demo
```
Observable.create { observer in
    observer.onNext("Hello world!") 
    observer.onCompleted()

return NopDisposable.instance
    }.subscribe { event in
        print(event)
    }

// outputs:
// Next(Hello world!) 
// Completed
```

---

### Sequence operators
* map
* flatMap
* filter
* throttle
* merge
* combineLatest

---

### [map](http://reactivex.io/documentation/operators/map.html)
```
let disposeBag = DisposeBag()

let formatter = NumberFormatter()
formatter.numberStyle = .spellOut

Observable<NSNumber>.of(123, 4, 56)
  .map {
	formatter.string(from: $0) ?? ""
  }
  .subscribe(onNext: {
	print($0)
  })
  .addDisposableTo(disposeBag)
```

---

### Bindings 
```swift
self.button.rx.tap
  .withLatestFrom(segmentedControl.rx.value)
  .map { selectedIndex in
	  return "You've selected #\(selectedIndex)."
  }
  .subscribe { message in
	  print(message)
  }
  .addDisposableTo(disposeBag)
```

---

### KVO 
```swift
view.rx.observe(CGRect.self, "frame")
	.subscribe(onNext: { frame in
		print("Got new frame \(frame)")
	}).disposed(by: disposeBag)
```

---

### Notifications
```
NotificationCenter.default
	.rx.notification(NSNotification.Name.UITextViewTextDidBeginEditing, object: myTextView)
	.map {  /*do something with data*/ }
```