为什么我不能用一根手指旋转我的 imageview Swift？

Question

所以我正在制作一个 DJ 应用程序，并且我有一个转盘，我想通过触摸向左和向右旋转。我让它在播放歌曲时移动，但不确定如何使用触摸让它旋转。

编辑******* 我让它工作，但我需要用一根手指而不是两根手指来旋转图像视图。我怎样才能让它发挥作用？谢谢

class ViewController: UIViewController, MPMediaPickerControllerDelegate {

    var angle: CGFloat = 0
    var rotate = UIRotationGestureRecognizer()

    override func viewDidLoad() {
        super.viewDidLoad()

        self.rotate = UIRotationGestureRecognizer(target: self, action: #selector(ViewController.rotate(_:)))
        self.leftTurnTable.addGestureRecognizer(self.rotate)
    }

    func rotate(r:UIRotationGestureRecognizer) {

        self.leftTurnTable.transform = CGAffineTransformMakeRotation(angle+r.rotation)

        if r.state == UIGestureRecognizerState.Ended {

            self.angle += r.rotation
        }
    }
}

Answer 1

override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {


     let touch = touches.first
    if touch!.view === leftTurnTable {
        let position = touch!.locationInView(self.view)
        let target = leftTurnTable.center
        let angle = atan2(target.y-position.y, target.x-position.x)
        leftTurnTable.transform = CGAffineTransformMakeRotation(angle)
    }
}

为什么我不能用一根手指旋转我的 imageview Swift？

Why cant I rotate my imageview with one finger Swift?

ios

swift

touchesmoved