ios - 缩放 CAShapeLayer 时的意外行为

Question

我正在使用以下代码来缩放 CAShapelayer 实例(即 self.view.layer.sublayers![0]):

class ViewController: UIViewController {   
override func viewDidLoad()
{
    super.viewDidLoad()
    self.view = Map(frame: CGRect(x: 0, y: 0, width: self.view.bounds.width, height: self.view.bounds.height))
    let pinchGR = UIPinchGestureRecognizer(target: self, action: #selector(self.didPinch(_:)))
    self.view.addGestureRecognizer(pinchGR)
}

@objc func didPinch(_ pinchGR: UIPinchGestureRecognizer)
{
    let transformation = CGAffineTransform(a: pinchGR.scale, b: 0, c: 0, d: pinchGR.scale, tx: 0, ty: 0)
    if pinchGR.state == .began || pinchGR.state == .changed
    {
        self.view.layer.sublayers![0].setAffineTransform(transformation)
    }
}}

class Map: UIView{
override init(frame: CGRect)
{
    super.init(frame: frame)
    self.backgroundColor = UIColor.blue
    drawTestShape()
}
required init?(coder aDecoder: NSCoder)
{
    super.init(coder: aDecoder)
}
func drawTestShape()
{
    let shapeLayer = CAShapeLayer()
    shapeLayer.frame = self.frame
    let path = UIBezierPath()
    shapeLayer.lineWidth = 5.0
    shapeLayer.fillColor = nil
    shapeLayer.strokeColor = UIColor.white.cgColor
    shapeLayer.backgroundColor = UIColor.red.cgColor
    path.move(to: CGPoint(x:200,y:200))
    path.addLine(to: CGPoint(x:300,y:300))
    path.addLine(to: CGPoint(x:100,y:300))
    path.close()
    shapeLayer.path = path.cgPath
    self.layer.addSublayer(shapeLayer)
}}

缩放在第一个捏合手势中正确执行。但是，当应用第二个捏合手势时，CAShapelayer 实例再次从其初始大小开始，而不是从第一次手势后的大小开始。

Answer 1

我真的不能支持缩放图层的想法，但如果你必须这样做，请尝试更多类似的东西；这是实现捏合手势识别器的标准模式，因此最好坚持使用它:

@IBAction func didPinch(_ pinchGR: UIPinchGestureRecognizer) {
    self.view.layer.sublayers![0].setAffineTransform(
        self.view.layer.sublayers![0].affineTransform().scaledBy(
            x:pinchGR.scale, y:pinchGR.scale))
    pinchGR.scale = 1.0;
}