协议扩展编译器错误中的Swift 2.2 #selector

5 回答

• 6

  我遇到了类似的问题 . 这就是我做的 .

  • 将协议标记为@objc .

  • 将我使用默认行为扩展的任何方法标记为可选 .

  • 然后使用Self . 在#selector中 .

  @objc public protocol UpdatableUserInterfaceType {
    optional func startUpdateUITimer()
    optional var updateInterval: NSTimeInterval { get }
    func updateUI(notif: NSTimer)
  }
  
  public extension UpdatableUserInterfaceType where Self: ViewController {
  
    var updateUITimer: NSTimer {
      return NSTimer.scheduledTimerWithTimeInterval(updateInterval, target: self, selector: #selector(Self.updateUI(_:)), userInfo: nil, repeats: true)
    }
  
    func startUpdateUITimer() {
      print(updateUITimer)
    }
  
    var updateInterval: NSTimeInterval {
      return 60.0
    }
  }
  

  回复于 2024-05-06T02:56:45+08:00
• 0

  您可以创建一个属性作为选择器...示例：

  protocol Tappable {
      var selector: Selector { get }
      func addTapGestureRecognizer()
  }
  
  extension Tappable where Self: UIView {
      func addTapGestureRecognizer() {
          let gesture = UITapGestureRecognizer(target: self, action: selector)
          addGestureRecognizer(gesture)
      }
  }
  
  class TapView: UIView, Tappable {
      var selector = #selector(TapView.tapGestureDetected(_:))
  
      func tapGestureDetected(gesture:UITapGestureRecognizer) {
          print("Tapped")
      }
  }
  

  错误停止显示，并且不再需要使用@objc装饰器设置协议和类 .

  这个解决方案不是最优雅的，但直到现在看起来还不错 .

  回复于 2024-05-06T02:56:45+08:00
• 24

  这个答案与Bruno Hecktheuers非常相似，但是我们选择将它作为参数传递给addTapGestureRecognizer函数，而不是让每个想要符合“Tappable”协议的人实现变量“selector” .

  protocol Tappable {
      func addTapGestureRecognizer(selector selector: Selector)
      func tapGestureDetected(gesture:UITapGestureRecognizer)
  }
  
  extension Tappable where Self: UIView {
      func addTapGestureRecognizer(selector selector: Selector)
          let gesture = UITapGestureRecognizer(target: self, action: selector)
          addGestureRecognizer(gesture)
      }
  }
  
  class TapView: UIView, Tappable {    
      func tapGestureDetected(gesture:UITapGestureRecognizer) {
          print("Tapped")
      }
  }
  

  然后只需将选择器传递到任何地方：

  addTapGestureRecognizer(selector: #selector(self.tapGestureDetected(_:)))
  

  这样我们就可以避免让实现此协议的人必须实现选择器变量，并且我们也避免使用“@objc”标记每个人使用此协议 . 像这种方法的感觉不那么臃肿 .

  回复于 2024-05-06T02:56:45+08:00
• 16

  这是一个使用Swift 3的工作示例 . 它使用标准的Swift协议，无需任何 @objc 装饰和私有扩展来定义回调函数 .

  protocol PlayButtonPlayable {
  
      // be sure to call addPlayButtonRecognizer from viewDidLoad or later in the display cycle
      func addPlayButtonRecognizer()
      func handlePlayButton(_ sender: UITapGestureRecognizer)
  
  }
  
  fileprivate extension UIViewController {
      @objc func _handlePlayButton(_ sender: UITapGestureRecognizer) {
          if let playable = self as? PlayButtonPlayable {
              playable.handlePlayButton(sender)
          }
      }
  }
  
  fileprivate extension Selector {
      static let playTapped =
          #selector(UIViewController._handlePlayButton(_:))
  }
  
  extension PlayButtonPlayable where Self: UIViewController {
  
      func addPlayButtonRecognizer() {
          let playButtonRecognizer = UITapGestureRecognizer(target: self, action: .playTapped)
          playButtonRecognizer.allowedPressTypes = [ NSNumber(value: UIPressType.playPause.rawValue as Int) ]
          view.addGestureRecognizer(playButtonRecognizer)
      }
  
  }
  

  回复于 2024-05-06T02:56:45+08:00
• 4

  我碰巧在侧栏看到这个，我最近遇到了同样的问题..不幸的是，由于Objective-C运行时限制你不能在协议扩展上使用@objc，我相信这个问题在今年年初就已经关闭了 .

  出现这个问题是因为在协议符合性之后添加了扩展，因此无法保证满足协议的一致性 . 也就是说，可以从NSObject子类和符合协议的任何东西中调用方法作为选择器 . 这通常是通过授权完成的 .

  这意味着您可以创建一个符合协议的空包装子类，并使用包装器从包装器中定义的协议调用其方法，协议中的任何其他未定义方法都可以传递给委托 . 还有其他类似的解决方案使用具体类的私有扩展，如UIViewController，并定义一个调用协议方法的方法，但这些方法也绑定到一个特定的类，而不是特定类的默认实现，恰好符合协议 .

  意识到您正在尝试实现协议函数的默认实现，该函数使用其自己的另一个协议函数来为其自己的实现定义值 . 噢！

  Protocol:

  public protocol CustomViewDelegate {
       func update()
       func nonDelegatedMethod()
  }
  

  View:

  使用委托，并定义一个包装器方法来安全地解包委托的方法 .

  class CustomView: UIView {
  
      let updateButton: UIButton = {
          let button = UIButton(frame: CGRect(origin: CGPoint(x: 50, y: 50), size: CGSize(width: 150, height: 50)))
          button.backgroundColor = UIColor.lightGray
          button.addTarget(self, action: #selector(doDelegateMethod), for: .touchUpInside)
          return button
      }()
  
      var delegate:CustomViewDelegate?
  
      required init?(coder aDecoder: NSCoder) {
          fatalError("Pew pew, Aghh!")
      }
  
      override init(frame: CGRect) {
          super.init(frame: frame)
          addSubview(updateButton)
      }
  
      @objc func doDelegateMethod() {
          if delegate != nil {
             delegate!.update()
          } else {
             print("Gottfried: I wanted to be a brain surgeon, but I had a bad habit of dropping things")
          }
       }
  
  
     }
  

  ViewController:

  使View Controller符合视图的委托：并实现协议的方法 .

  class ViewController: UIViewController, CustomViewDelegate {
  
      let customView = CustomView(frame: CGRect(origin: CGPoint(x: 100, y: 100), size: CGSize(width: 200, height: 200)))
  
      override func viewDidLoad() {
          super.viewDidLoad()
          customView.backgroundColor = UIColor.red
          customView.delegate = self //if delegate is not set, the app will not crash
          self.view.addSubview(customView)
      }
  
      // Protocol -> UIView Button Action -> View Controller's Method
      func update() {
          print("Delegating work from View that Conforms to CustomViewDelegate to View Controller")
      }
  
      //Protocol > View Controller's Required Implementation
      func nonDelegatedMethod() {
  
         //Do something else 
  
     }
  }
  

  请注意，视图控制器只需要符合委托，并且没有设置视图的某些属性的选择器，这将视图（和它的协议）与视图控制器分开 .

  您已经有一个名为TapView的UIView，它继承自UIView和Tappable，因此您的实现可能是：

  Protocol:

  protocol TappableViewDelegate {
      func tapGestureDetected(gesture:UITapGestureRecognizer)
  }
  

  TappableView:

  class TappableView: UIView {
  
      var delegate:TappableViewDelegate?
  
      required init?(coder aDecoder: NSCoder) {
          fatalError("Pew pew, Aghh!")
      }
  
      override init(frame: CGRect) {
          super.init(frame: frame)
  
          let gesture = UITapGestureRecognizer(target: self, action: #selector(doDelegateMethod(gesture:)))
          addGestureRecognizer(gesture)
      }
  
      @objc func doDelegateMethod(gesture:UITapGestureRecognizer) {
          if delegate != nil {
              delegate!.tapGestureDetected(gesture: gesture)
          } else {
              print("Gottfried: I wanted to be a brain surgeon, but I had a bad habit of dropping things")
          }
      }
  
  }
  

  ViewController:

  class ViewController: UIViewController, TappableViewDelegate {
  
      let tapView = TappableView(frame: CGRect(origin: CGPoint(x: 100, y: 100), size: CGSize(width: 200, height: 200)))
  
      override func viewDidLoad() {
          super.viewDidLoad()
          tapView.backgroundColor = UIColor.red
          tapView.delegate = self
          self.view.addSubview(tapView)
      }
  
      func tapGestureDetected(gesture: UITapGestureRecognizer) {
          print("User did tap")
     }
  
  }
  

  回复于 2024-05-06T02:56:45+08:00