Question

我正在尝试缩放图像视图，因为我将scrollView滚动到屏幕顶部。这是我的代码：

func scrollViewDidScroll(_ scrollView: UIScrollView) {
    let offset = scrollView.contentOffset.y
    if (offset <= 0) {
        let ratio: CGFloat = -offset*1.0 / UIScreen.main.bounds.height
        self.coverImageView.transform = CGAffineTransform(scaleX: 1.0 + ratio, y: 1.0 + ratio)
    }
}

这会在我向上滚动时缩放图像，但由于我也在向上滚动，我的视图会下降，并在图像展开时显示背后的白色背景。我该如何防止这种情况发生？

Answer 1

听起来像滚动视图并不适合你想要做的事情。如何使用手势识别器呢？这些方面的东西：

override func viewDidLoad() {
  super.viewDidLoad()
  coverImageView.isUserInteractionEnabled = true
  let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(didPan))
  coverImageView.addGestureRecognizer(panGestureRecognizer)
}

func didPan(panGestureRecognizer: UIPanGestureRecognizer) {
  let translation = panGestureRecognizer.translation(in: coverImageView)
  if translation.y > 0 {
    let zoomRatio = (translation.y * 0.1) + 1.0
    coverImageView.transform = CGAffineTransform(scaleX: zoomRatio, y: zoomRatio)
  }
}

你必须四处游戏才能让它按照你想要的方式行事，但它应该足以让你开始。

Swift：当我在scrollview

1 个答案: