单例实例(Singleton Instance)

 好的，我终于找到了一个解决方案，如何在Mac OS X中围绕视图拖动Label或TextField（NSTextField）控件。 我已经完成了解决方案： 
 
 在ViewController类中创建一个属性 
 
class ViewController:  NSViewController {
    var mouseDownLocation: CGPoint?

}
 
 在覆盖mouseDown事件中 
 
var mouseDownEvent: NSEvent?


@IBAction override func mouseDown(theEvent: NSEvent) {

    var event_location: NSPoint!
    event_location = theEvent.locationInWindow

    var cntrl_id = NSTextField()
    var cntrl_frame = NSRect()
    var cntrl_name = String()
    var cntrl_value = String()
    var hit = Bool()

    for view in self.view.subviews as [NSView] {
        if let ct = view as? NSTextField {
            cntrl_name = ct.identifier!
            cntrl_id = ct
            cntrl_frame = ct.frame
            cntrl_value = ct.stringValue
            hit = cntrl_frame.contains(event_location)
            if hit {
                controlToMove = cntrl_id
                lastLocation = controlToMove?.frame.origin
                break
            }
        }
    }

    //figure out the difference of where the mouse went down at in the
    //control frame in relation to the control frame origin
    let dx = event_location.x - (controlToMove?.frame.origin.x)!
    let dy = event_location.y - (controlToMove?.frame.origin.y)!
    let mouseDownInCntrlFrame = CGPoint(x: dx, y: dy)
    mouseDownLocation = mouseDownInCntrlFrame

}
 
 现在在覆盖mouseDragged事件中 
 
@IBAction override func mouseDragged(theEvent: NSEvent) {

    let dragPoint = theEvent.locationInWindow

    if controlToMove != nil {

        var cntrl_location = CGPoint();
        cntrl_location.x = controlToMove!.frame.origin.x
        cntrl_location.y = controlToMove!.frame.origin.y
        print( "cntrl_location X,Y = \(cntrl_location)" )

        let previousLocation = cntrl_location

        var location = CGPoint()
        location = dragPoint
        location.x -= (mouseDownLocation?.x)!
        location.y -= (mouseDownLocation?.y)!

        var delta_x = CGFloat()
        var delta_y = CGFloat()
        delta_x = location.x - previousLocation.x
        delta_y = location.y - previousLocation.y

        // move label
        cntrl_location = CGPointMake(location.x + delta_x, location.y + delta_y);

        controlToMove!.frame.origin.x = cntrl_location.x
        controlToMove!.frame.origin.y = cntrl_location.y

    }

}
 
 这将允许您在单击并拖动的视图周围拖动任何NSTextField。 它并不像我想的那样平滑，因为你在视图中拖动它时只需要一点希望控件。 但是考虑到互联网上没有其他任何关于如何拖动OS X控件的信息（有一些关于如何拖动图像的博客和信息 - 但即使是那些更像是拖放式解决方案）快速浏览视图这是一个有效的解决方案。 我相信一位经验丰富的OS X Xcode大师可以改进这个解决方案 - 如果OS X开发人员希望提供一些经验，我欢迎对此解决方案进行改进。 

Okay I have a solution finally to the question how do you drag a Label or TextField (NSTextField) control in Mac OS X around a view. I have finalized the solution:
 
In the ViewController class create a property
 
class ViewController:  NSViewController {
    var mouseDownLocation: CGPoint?

}
 
In the override mouseDown event
 
var mouseDownEvent: NSEvent?


@IBAction override func mouseDown(theEvent: NSEvent) {

    var event_location: NSPoint!
    event_location = theEvent.locationInWindow

    var cntrl_id = NSTextField()
    var cntrl_frame = NSRect()
    var cntrl_name = String()
    var cntrl_value = String()
    var hit = Bool()

    for view in self.view.subviews as [NSView] {
        if let ct = view as? NSTextField {
            cntrl_name = ct.identifier!
            cntrl_id = ct
            cntrl_frame = ct.frame
            cntrl_value = ct.stringValue
            hit = cntrl_frame.contains(event_location)
            if hit {
                controlToMove = cntrl_id
                lastLocation = controlToMove?.frame.origin
                break
            }
        }
    }

    //figure out the difference of where the mouse went down at in the
    //control frame in relation to the control frame origin
    let dx = event_location.x - (controlToMove?.frame.origin.x)!
    let dy = event_location.y - (controlToMove?.frame.origin.y)!
    let mouseDownInCntrlFrame = CGPoint(x: dx, y: dy)
    mouseDownLocation = mouseDownInCntrlFrame

}
 
Now in the override mouseDragged event
 
@IBAction override func mouseDragged(theEvent: NSEvent) {

    let dragPoint = theEvent.locationInWindow

    if controlToMove != nil {

        var cntrl_location = CGPoint();
        cntrl_location.x = controlToMove!.frame.origin.x
        cntrl_location.y = controlToMove!.frame.origin.y
        print( "cntrl_location X,Y = \(cntrl_location)" )

        let previousLocation = cntrl_location

        var location = CGPoint()
        location = dragPoint
        location.x -= (mouseDownLocation?.x)!
        location.y -= (mouseDownLocation?.y)!

        var delta_x = CGFloat()
        var delta_y = CGFloat()
        delta_x = location.x - previousLocation.x
        delta_y = location.y - previousLocation.y

        // move label
        cntrl_location = CGPointMake(location.x + delta_x, location.y + delta_y);

        controlToMove!.frame.origin.x = cntrl_location.x
        controlToMove!.frame.origin.y = cntrl_location.y

    }

}
 
This will let you drag any NSTextField around the view that you click down on and drag. It is not quite as smooth as I would like there is just a bit of hoping of the control as you drag it around the view. But considering that there is no other information anywhere on the internet on how to drag an OS X control (there are a couple of blogs and information on how to drag an image - but even those are more of a drag and drop type solution) in swift around a view this is a solution that works. I am sure an experienced OS X Xcode guru could improve on this solution - I welcome a refinement to this solution if some experience OS X developer wishes to contribute.