是否可以從touchesBegan或touchesMoved內部取消觸摸？

Question

在我的UIViewController主視圖中，我有一個mapView和另一個視圖（比方說視圖A），它位於mapView上方。它們都具有等於self.view.bounds的框架。視圖A是一個可調整大小的矩形，與用於裁剪圖像的矩形相似。我的目標是讓用戶在地圖上指定一個區域。所以，我希望用戶能夠放大地圖以及改變矩形的寬度和高度比例，因爲只讓視圖A成爲不可實現的方形會限制它太多。

我從GitHub https://github.com/justwudi/WDImagePicker中得到了這個項目，我從中使用了可調整大小的矩形功能。在Github鏈接的第二張圖片中，有一個8個點的矩形和一個外面的陰影區域。如果用戶觸摸陰影區域，我希望能夠將觸摸傳遞到視圖A後面的地圖。只有當用戶點擊點或點上的區域（以便他想調整矩形的大小）時，我希望視圖A能夠識別觸摸。所以，我修改上的視圖觸摸的代碼，並有這樣的：

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) { 
    if let touch = touches.first { 

     if cropBorderView.frame.contains(touch.location(in: self)){ 
      print("touch contains - touchesbegan") 
      //self.isUserInteractionEnabled = true 
     } 
     else{ 
      print("Touch does not contain - touchesbegan") 
      self.touchesCancelled(touches, with: event) 
      //return 
     } 
     let touchPoint = touch.location(in: cropBorderView) 

     anchor = self.calculateAnchorBorder(touchPoint) 
     fillMultiplyer() 
     resizingEnabled = true 
     startPoint = touch.location(in: self.superview) 
    } 
} 

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) { 
    print("inside touches moved") 
    if let touch = touches.first { 
     if cropBorderView.frame.contains(touch.location(in: self)){ 
      print("touch contains - touchesmoved") 
      //self.isUserInteractionEnabled = true 
     } 
     else{ 
      print("Touch does not contain - touchesmoved ") 
      self.touchesCancelled(touches, with: event) 
      //return 
     } 

     if resizingEnabled! { 
      self.resizeWithTouchPoint(touch.location(in: self.superview)) 
     } 
    } 
} 

它確實承認，當我點擊內外觸摸，因爲我想要的，但是當我點擊外面停不觸摸。這意味着撥打self.touchesCancelled(touches, with: event)不起作用。調用返回會導致崩潰，並且不起作用。有沒有解決這個問題的方法？

謝謝你的時間和考慮。

Answer 1

touchesCancelled(_:with:)只是通知UITouch，它不會這樣工作。 據我瞭解，你實現觸摸處理器在您的覆蓋UIView，如果是的話，你可以嘗試從UIControl類implementation與cancelTracking(with:)函數調用替換到self.touchesCancelled(touches, with: event)：

else { 
    print("Touch does not contain - touchesmoved ") 
    self.cancelTracking(with event) 
} 

---

更新解決方案，根據hitTest:

我檢查了可能的解決方案，似乎你可以使用hitTest:以避免不必要的觸摸識別。下面的例子是斯威夫特遊樂場，您可以點擊並拖動觸摸，並在控制檯中看到發生了什麼：

import UIKit 
import PlaygroundSupport 

class JSGView : UIView { 

    var centerView = UIView() 

    override func didMoveToSuperview() { 
     frame = CGRect(x: 0, y: 0, width: 320, height: 480) 
     backgroundColor = UIColor.clear 

     centerView.frame = CGRect(x: 110, y: 190, width: 100, height: 100) 
     centerView.backgroundColor = UIColor.blue 
     addSubview(centerView) 
    } 

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) { 
     dump(event) 
    } 

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) { 
     if let touch = touches.first { 
      if (hitTest(touch.location(in: self), with: event) != nil) { 
       print("Touch passed hit test and seems valid") 
       super.touchesCancelled(touches, with: event) 
       return 
      } 
     } 

     print("Touch isn't passed hit test and will be ignored") 
     super.touchesMoved(touches, with: event) 
    } 

    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? { 
     if centerView.bounds.contains(centerView.convert(point, from: self)) { 
      return centerView 
     } 
     return nil 
    } 
} 

class JSGViewController : UIViewController { 
    override func viewDidLoad() { 
     super.viewDidLoad() 
     view.frame = CGRect(x: 0, y: 0, width: 320, height: 480) 
     let customView = JSGView() 
     view.addSubview(customView) 
    } 
} 

let controller = JSGViewController() 
PlaygroundPage.current.liveView = controller.view