如何在 Swift 中使扩展中的计时器无效

Question

我试图在扩展程序中添加计时器属性。代码如下

 @objc public extension RCTTouchHandler {
  static let kSessionTimer = "sessionTimer"
  
   var sessionTimer: Timer {
    get {
      return objc_getAssociatedObject(self, RCTTouchHandler.kSessionTimer) as? Timer ?? Timer.scheduledTimer(timeInterval: RCTTouchHandler.kSessionExpiredDuration, target: self, selector: #selector(touchSessionExpiration), userInfo: nil, repeats: false)
    }

    set(timer) {
      objc_setAssociatedObject(self, RCTTouchHandler.kSessionTimer, self, .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }
  }

  @objc func touchSessionExpiration() {
    print("session expired")
  }

  deinit {
    self.sessionTimer.invalidate()
  }
}

然后，sessionTimer对该对象有强引用，同时，该对象强保留sessionTimer。为了避免保留周期和内存泄漏，我应该在对象被取消初始化时使计时器无效。但是，我在尝试使此扩展中的 deinit 函数中的计时器无效时遇到以下错误。

Deinitializers may only be declared within a class

根据Swift Doc

Extensions can add new convenience initializers to a class, but they cannot add new designated initializers or deinitializers to a class. Designated initializers and deinitializers must always be provided by the original class implementation.

所以我想知道我应该如何在此扩展程序中正确地使计时器失效？

Answer 1

如您所说，您无法在扩展中实现 deinit { }。

您可以创建自己的对象并在那里实现 deinit { } 而不是到处使用 RCTTouchHandler，而是使用您自己的对象：

@objc extension RCTTouchHandler {
    static let kSessionTimer = "sessionTimer"
}

public class MyTouchHandler: RCTTouchHandler {
    private var timer: Timer? = nil

    var sessionTimer: Timer {
        get {
            guard let timer = timer else {
                let newTimer = Timer.scheduledTimer(timeInterval: RCTTouchHandler.kSessionExpiredDuration, target: self, selector: #selector(touchSessionExpiration), userInfo: nil, repeats: false)
                self.timer = newTimer
                return newTimer
            }
            return timer
        }

        set(timer) {
            self.timer = timer
        }
    }

    @objc func touchSessionExpiration() {
        print("session expired")
    }

    deinit {
        self.timer?.invalidate()
    }
}

如何在 Swift 中使扩展中的计时器无效

How to invalidate timer in extension in Swift

ios

swift

swift-extensions