ios - 如何处理 UIImageview 的 UIScrollView 缩放中的偏移量？

Question

简单地说，我有一个 UIScrollView 用于在该 View 内缩放的 View :UIImageView。

这是我只显示图像时的样子:

当我捏的时候:

当我捏合后向下滑动时:

现在我有了不想看到的黑色空间。有没有办法设置一些偏移量并防止在图像后滚动太远？

在代码中我简单地使用:

//MARK: - UIScrollViewDelegate

public func viewForZooming(in scrollView: UIScrollView) -> UIView? {
    return photoImageView
}

Answer 1

简单地实现UIScrollViewDelegate:

//MARK: - UIScrollViewDelegate

public func viewForZooming(in scrollView: UIScrollView) -> UIView? {
    return photoImageView
}

public func scrollViewDidZoom(_ scrollView: UIScrollView) {

    let imageViewSize = photoImageView.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

    if verticalPadding >= 0 {
        scrollView.contentInset = UIEdgeInsets(top: verticalPadding, left: horizontalPadding, bottom: verticalPadding, right: horizontalPadding)
    } else {
        scrollView.contentSize = imageViewSize
    }
}

并在 viewDidLoad 上准备 View :

private func setupInitialView() {

    photoImageView.sizeToFit()

    let imageViewSize = photoImageView.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.setZoomScale(scrollView.minimumZoomScale, animated: false)

    scrollViewDidZoom(scrollView)
}