Question

我正在尝试使用UITouch将按钮从一个位置拖动到另一个位置。但是我无法拖动它。我在添加按钮目标时面临问题...

我的代码 -

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
     let btn_swap = UIButton.buttonWithType(UIButtonType.Custom) as UIButton!
    btn_swap .setTitle("Drag Me", forState: UIControlState.Normal)
    btn_swap.backgroundColor = UIColor.yellowColor()

    btn_swap.addTarget(self, action: "wasDragged:", forControlEvents: UIControlEvents.TouchDragInside)

    btn_swap.frame = CGRectMake((self.view.bounds.size.width - 100)/2.0,
        (self.view.bounds.size.height - 50)/2.0,
        100, 50)

    self.view.addSubview(btn_swap)
    self.creation_of_btn()
 }

func wasDragged (buttn : UIButton, event :UIEvent)
{
    var touch : UITouch = event.touchesForView(buttn) . anyObject() as UITouch
    var previousLocation : CGPoint = touch .previousLocationInView(buttn)
     var location : CGPoint = touch .locationInView(buttn)
    var delta_x :CGFloat = location.x - previousLocation.x
      var delta_y :CGFloat = location.y - previousLocation.y
    buttn.center = CGPointMake(buttn.center.x + delta_x,
        buttn.center.y + delta_y);

}

Answer 1

您为按钮wasDragged:指定了错误的选择器。由于您的操作方法看起来像

func wasDragged (buttn : UIButton, event :UIEvent)
{
}

slector应为wasDragged: event:。

btn_swap.addTarget(self, action: "wasDragged:event:", forControlEvents: UIControlEvents.TouchDragInside)

Answer 2

事件TouchDragInside还需要将事件参数作为第二个参数传递。

斯威夫特1：

https://stackoverflow.com/a/24547115/5078763

斯威夫特2：

btn_swap.addTarget(self,action: #selector(wasDragged(_:event:)),forControlEvents: .TouchDragInside)

func wasDragged(btnVar : UIButton, evtVar :UIEvent)
{
    let touch : UITouch = (evtVar.touchesForView(btnVar)?.first)! as UITouch
    let previousLocation : CGPoint = touch .previousLocationInView(btnVar)
    let location : CGPoint = touch .locationInView(btnVar)
    let delta_x :CGFloat = location.x - previousLocation.x
    let delta_y :CGFloat = location.y - previousLocation.y
    btnVar.center = CGPointMake(btnVar.center.x + delta_x,
                               btnVar.center.y + delta_y);
}

Answer 3

迅速4.2

func wasDragged (buttn : UIButton, event :UIEvent){}


btn_swap.addTarget(self,action: #selector(wasDragged(buttn:event:)),for: .touchDragInside)

Swift-拖动按钮从一个位置到另一个位置

3 个答案: