Swift：如何为CALayer启用缩放功能？ [英] Swift: How to enable pinch-to-zoom for CALayer?

问题描述

我一直在尝试滚动和缩放多个多边形路径的CALayer，特别是CAShapeLayer。我将CALayer添加到了UIScrollView中，该UIScrollView已成功启用了在CALayer上滚动。

I have been trying to scroll and zoom a CALayer, specifically a CAShapeLayer, of several polygon paths. I added the CALayer to a UIScrollView which has successfully enabled scrolling around the CALayer.

但是，缩小缩放不起作用。一些教程已经实现了使用UIScrollViewDelegate缩放UIImageView的方法，基本上是这样的：

However, pinch to zoom is not working. Several tutorials have implemented zooming a UIImageView with the UIScrollViewDelegate essentially like so:

@IBOutlet var scrollView : UIScrollView!
var imageView = UIImageView()
scrollView.addSubview(imageView)

func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
    return imageView
}

但是CALayer与UIView不兼容，我有找不到关于调和差异的信息。

But CALayer is incompatible with UIView and I have found no information on reconciling the difference.

在Swift中，有没有类似的本地方法来缩放CALayer？逃避我的事情真的很简单吗？任何帮助，将不胜感激;

Is there a similar native way to zoom a CALayer in Swift? Is it something really simple that escaped me? Any help would be appreciated; apologies if I am missing the obvious.

推荐答案

经过大量挖掘后，我发现相关的 Apple的文档 。事实证明，如果设置正确，则在CALayers上会自动处理捏缩放。我为Swift修改了演示代码，并提出了适用于我的基本结构。

After much digging I found the related documentation from Apple. Turns out pinch-to-zoom is handled automatically on CALayers if they are set up correctly. I adapted the demo code for Swift and came up with this basic structure, which worked for me.

class ViewController: UIViewController, UIScrollViewDelegate {

    @IBOutlet var scrollView : UIScrollView!
    var layerView = UIView()
    var shapeLayer= CAShapeLayer()

    func viewForZoomingInScrollView(scrollView: UIScrollView) -> UIView? {
        return layerView // Specify the layer to scroll, cannot be the UIScrollView used for scrolling
    }
    func scrollViewDidEndZooming(scrollView: UIScrollView, withView view: UIView!, atScale scale: CGFloat) {
        // This was noted as required but no inner code is necessary
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        layerView.layer.addSublayer(shapeLayer) // Attach layer to the canvas view
        scrollView.addSubview(layerView) // Attach the views
        // ... Add layer content, set max and min scaling values as well as layer/view sizes to encompass content
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}

我希望这对其他人有帮助！

I hope this helps someone else!

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