的NSView不接收mouseUp事件：事件时鼠标按钮的视图

Question

外释放我有一个自定义NSView子类与（例如）以下方法：

override func mouseDown(with event: NSEvent) { Swift.print("mouseDown") } 
override func mouseDragged(with event: NSEvent) { Swift.print("mouseDragged") } 
override func mouseUp(with event: NSEvent) { Swift.print("mouseUp") } 

只要鼠标（按钮）被按下，拖动并释放视图内的所有内容，这工作正常。但是，当鼠标在视图内部被压低时，移动到视图外部，并且只有这样才能释放，我永远不会收到事件。

P.S .:呼叫super的实施没有帮助。

Answer 1

Apple的鼠标事件文档中的Handling Mouse Dragging Operations部分提供了一个解决方案：显然，我们在使用鼠标跟踪循环跟踪事件时收到了mouseUp事件。

下面是从文档中示例代码的变种，适合雨燕3：

override func mouseDown(with event: NSEvent) { 
    var keepOn = true 

    mouseDownImpl(with: event) 

    // We need to use a mouse-tracking loop as otherwise mouseUp events are not delivered when the mouse button is 
    // released outside the view. 
    while true { 
     guard let nextEvent = self.window?.nextEvent(matching: [.leftMouseUp, .leftMouseDragged]) else { continue } 
     let mouseLocation = self.convert(nextEvent.locationInWindow, from: nil) 
     let isInside = self.bounds.contains(mouseLocation) 

     switch nextEvent.type { 
     case .leftMouseDragged: 
      if isInside { 
       mouseDraggedImpl(with: nextEvent) 
      } 

     case .leftMouseUp: 
      mouseUpImpl(with: nextEvent) 
      return 

     default: break 
     } 
    } 
} 

func mouseDownImpl(with event: NSEvent) { Swift.print("mouseDown") } 
func mouseDraggedImpl(with event: NSEvent) { Swift.print("mouseDragged") } 
func mouseUpImpl(with event: NSEvent) { Swift.print("mouseUp") }