放大 UIScrollView 时未调用 scrollViewDidEndZooming

Question

这可能是 Xcode 错误？我在 UIScrollView 中有一个 UIImage 以编程方式在代码中完成。用户可以使用缩放手势或双击图像来放大图像。这部分一切正常。

接下来，我尝试使用以下函数scrollViewDidEndZooming 在缩放手势或双击后检测滚动视图何时完成缩放。但是，scrollViewDidEndZooming 永远不会被调用，并且不会打印 I just finished zooming! 行

代码不工作：

func scrollViewDidEndZooming(scrollView: UIScrollView, with view: UIView?, atScale scale: CGFloat) {
    print("I just finished zooming!")
}

问题：

这里可能发生了什么，为什么不是scrollViewDidEndZooming(...) 被叫了？

注意：我没有运气就参考了以下文档。 https://developer.apple.com/reference/uikit/uiscrollviewdelegate/1619407-scrollviewdidendzooming

---

完整代码：

class ScrollViewController: UIViewController, UIScrollViewDelegate {
    var scrollView: UIScrollView!
    var imageView: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()

        imageView = UIImageView(image: UIImage(named: "image.png"))

        scrollView = UIScrollView(frame: view.bounds)
        scrollView.backgroundColor = UIColor.blackColor()
        scrollView.contentSize = imageView.bounds.size
        scrollView.autoresizingMask = [UIViewAutoresizing.FlexibleWidth, UIViewAutoresizing.FlexibleHeight]

        scrollView.contentOffset = CGPoint(x: 1000, y: 450)

        scrollView.addSubview(imageView)
        view.addSubview(scrollView)

        scrollView.delegate = self
        setZoomScale()
        setupGestureRecognizer()
    }

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

    override func viewWillLayoutSubviews() {
        setZoomScale()
    }

    func setZoomScale() {
        let imageViewSize = imageView.bounds.size
        let scrollViewSize = scrollView.bounds.size
        let widthScale = scrollViewSize.width / imageViewSize.width
        let heightScale = scrollViewSize.height / imageViewSize.height

        scrollView.minimumZoomScale = min(widthScale, heightScale)
        scrollView.zoomScale = 1.0
    }

    func scrollViewDidZoom(scrollView: UIScrollView) {
        let imageViewSize = imageView.frame.size
        let scrollViewSize = scrollView.bounds.size
        let verticalPadding = imageViewSize.height < scrollViewSize.height ? (scrollViewSize.height - imageViewSize.height) / 2 : 0
        let horizontalPadding = imageViewSize.width < scrollViewSize.width ? (scrollViewSize.width - imageViewSize.width) / 2 : 0

        scrollView.contentInset = UIEdgeInsets(top: verticalPadding, left: horizontalPadding, bottom: verticalPadding, right: horizontalPadding)
    }

    func scrollViewDidEndZooming(scrollView: UIScrollView, with view: UIView?, atScale scale: CGFloat) {
        print("I just finished zooming!")
    }

    func setupGestureRecognizer() {
        let doubleTap = UITapGestureRecognizer(target: self, action: "handleDoubleTap:")
        doubleTap.numberOfTapsRequired = 2
        scrollView.addGestureRecognizer(doubleTap)
    }

    func handleDoubleTap(recognizer: UITapGestureRecognizer) {
        if (scrollView.zoomScale > scrollView.minimumZoomScale) {
            scrollView.setZoomScale(scrollView.minimumZoomScale, animated: true)
        } else {
            scrollView.setZoomScale(scrollView.maximumZoomScale, animated: true)
        }
    }
}

Answer 1

你犯了一个小错误。试试这个代码：

    func scrollViewDidEndZooming(scrollView: UIScrollView, withView view: UIView?, atScale scale: CGFloat) {
    print("I just finished zooming!")
}