//定義protocol
protocol someProtocol {
 var clickCount: Int { set get }
 func ClickEvent(action: String,value: NSNumber)
}

extension A: someProtocol{
 var clickCount: int { set get } 
 func ClickEvent(action: String,value: NSNumber){
  //實現(xiàn)代碼
 }
}

extension someProtocol where Self: UIViewController{
 var otherProperty: String{
  return "something you want"
 }

 func handleError(error: String) {
  //實現(xiàn)代碼
}}

//nameTextField是一個UITextField控件，可以直接通過.rx.text獲取到該控件中輸入內(nèi)容的事件序列，然后再進行處理

let nameObservable = nameTextField.rx.text .shareReplay(1).map {
 $0!.characters.count > 0 
}

//registerButton是一個UIButton，通過.rx.tap能獲取到該button的點擊事件序列
registerButton.rx.tap .bindTo(someObservar) .addDisposableTo(disposeBag)

/// Extend NSObject with `rx` proxy.將所有NSObject子類都遵循ReactiveCompatible協(xié)議 
extension NSObject: ReactiveCompatible { }
 //ReactiveCompatible這個協(xié)議中擴展了rx屬性，類型為struct類型的Reactive
extension ReactiveCompatible {
 /// Reactive extensions.
 public var rx: Reactive {
 get {
  return Reactive(self) //此處返回Reactive實體，將self賦給base屬性
 }
 set {
  // this enables using Reactive to "mutate" base object
 }
 }
}

public struct Reactive<Base>{ 
 /// Base object to extend. 
 public let base: Base 
 /// Creates extensions with base object. 
 ///
 /// - parameter base: Base object. 
 public init(_ base: Base) {  
  self.base = base //上面的return Reactive(self)，將self賦給了base
 }
}

//點擊事件擴展，可通過button.rx.tap來觀察訂閱
extension Reactive where Base: UIButton {
 /// Reactive wrapper for `TouchUpInside` control event.
 public var tap: ControlEvent {
  return controlEvent(.touchUpInside)
 } 
}

//擴展方法，可通過綁定Observable來動態(tài)修改UIButton的title和image
extension Reactive where Base: UIButton {
 /// Reactive wrapper for `setTitle(_:for:)`
 public func title(for controlState: UIControlState = []) -> UIBindingObserver<Base, String?> {
  return UIBindingObserver<Base, String?>(UIElement: self.base) { (button, title) -> () in
   button.setTitle(title, for: controlState)
  }
 }

 /// Reactive wrapper for `setImage(_:for:)`
 public func image(for controlState: UIControlState = []) -> UIBindingObserver<Base, UIImage?> {
  return UIBindingObserver<Base, UIImage?>(UIElement: self.base) { (button, image) -> () in
   button.setImage(image, for: controlState)
  }
 }

 /// Reactive wrapper for `setBackgroundImage(_:for:)`
 public func backgroundImage(for controlState: UIControlState = []) -> UIBindingObserver<Base, UIImage?> {
  return UIBindingObserver<Base, UIImage?>(UIElement: self.base) { (button, image) -> () in
   button.setBackgroundImage(image, for: controlState)
  }
 }
}

//利用限定擴展來自定義對UIButton的Reactive擴展 可以通過rx來訪問
extension Reactive where Base:UIButton{
 var btnValidState:UIBindingObserver<Base,Bool>{
  return UIBindingObserver(UIElement: base, binding: { (button, valid) in
   button.isEnabled = valid
   button.backgroundColor = valid ? mainColor : bgGrayColor2
  })
 }
}
//將用戶名和密碼的String序列轉(zhuǎn)換成Bool序列
let nameObservable = userNameText.rx.text .shareReplay(1).map {
   $0!.characters.count > 0
 }
let passObservable = passwordText.rx.text .shareReplay(1).map {
   $0!.characters.count > 0
 }
//將以上兩個序列合成一個序列，綁定到我們擴展的btnValidState屬性上
//可以看到此時可以通過loginBtn.rx.btnValidState獲取到，這樣保持了RxSwift代碼的一致性
 _ = Observable.combineLatest(nameObservable,passObservable){$0 && $1}.bind(to: loginBtn.rx.btnValidState).disposed(by: disposeBag)