RxSwift: Observables

• Rx Observables are intended for composing flows and sequences of asynchronous data.
• An Observable is just a sequence with special abilities. For example, it is asynchronous.
• Observable is a sequence definition that must be subscribed to for anything to really happen.
• Observables must be defined as being a specific type if the type cannot be inferred.
• Observables produce events. We say that they are “emitting”.
• Observables emit next events until an error event or completion event occurs.
• When an error or completion event occurs, this results in termination and no more events get emitted.
• An Observer subscribes to an Observable.
• The Observer reacts to what the Observable emits.
• Events can contain:
  • Values (Numbers, instances of a custom type).
  • Gesture recognisers (Tap).

Examples of creating observable sequences:

let championsSequence = Observable.just("Celtic")

let titlesInARow = Observable.from([1,2,3,4,5,6,7,8])

Example of subscribing to an observable:

let disposeBag = DisposeBag()

let champions = Observable.just("Celtic!")

champions.subscribe(onNext: { [weak self] champs in
  print(champs)
})
.disposed(by: disposeBag)

Example of a tap event:

signInButton
  .rx.tap
  .asObservable()
  .subscribe(onNext: { [unowned self] in
		self.signIn() })
  .disposed(by: disposeBag)

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