如何使用touches方法拖动UIImageView

Question

我试图通过触摸屏幕来拖动屏幕上的UIImageView。但是我希望能够不断地移动雪碧，目前我的代码只将精灵移动到我触摸的位置，如果我在屏幕上停留了一段时间，然后移动，精灵就会跟着移动。但是，我不想“不得不”触摸UIImageView来激活移动，我想要触摸屏幕上的任何位置，并从该UIImageView中从其当前位置得到一个移动响应。

这是我的密码。

var location = CGPoint()

override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
    if let touch = touches.first {
        location = touch.locationInView(self.view)
        ImageView.center = location}

}

override func prefersStatusBarHidden() -> Bool {
    return true
}

感谢您提供的任何帮助。

Answer 1

这里有一个更简单的实现。只需记住触摸的最后位置并计算差异，并使用差异设置图像的新位置。

var lastLocation = CGPoint()
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    if let touch = touches.first {
        self.lastLocation = touch.locationInView(self.view)
    }
}
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
    if let touch = touches.first {
        let location = touch.locationInView(self.view)
        self.imageView.center = CGPoint(x: (location.x - self.lastLocation.x) + self.imageView.center.x, y: (location.y - self.lastLocation.y) + self.imageView.center.y)
        lastLocation = touch.locationInView(self.view)
    }
}

Answer 2

下面是我为UIImageView编写的代码。代替img，您需要使用您的sprite对象。

您需要创建3个全局变量。

var offset: CGPoint
var isHold: Bool
var timerToCheckHold: NSTimer

使用触摸的方法。

func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent) {
    var touch: UITouch = touches.first!
    var location: CGPoint = touch.locationInView(self.view!)
    var imgCenter: CGPoint = img.center
    offset = CGPointMake(img.center.x - location.x, imgCenter.y - location.y)
    timerToCheckHold = NSTimer.scheduledTimerWithTimeInterval(0.5, target: self, selector: "timerToUpdateHold", userInfo: nil, repeats: false)
}

func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent) {
    if timerToCheckHold != nil && timerToCheckHold.isValid() {
        timerToCheckHold.invalidate()
    }
    if isHold {
        var touch: UITouch = touches.first!
        var location: CGPoint = touch.locationInView(self.view!)
        var newcenter: CGPoint = CGPointMake(offset.x + location.x, offset.y + location.y)
        img.center = newcenter
    }
}

func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent) {
    if timerToCheckHold != nil && timerToCheckHold.isValid() {
        timerToCheckHold.invalidate()
    }
    isHold = false
}

此外，您还需要实现timer方法。

func timerToUpdateHold() {
    isHold = true
}