一步步:
1 - 打开故事板并在顶部添加具有这些约束的图像视图(选择您的宽高比):
2 - 为您的uiimage选择aspectFill模式和clipSubviews
3 - 在 viewController 顶部添加一个 UIScrollView,其中包含一个子视图。有关使用scrollView自动布局的所有详细信息:http://natashatherobot.com/ios-autolayout-scrollview/
4 - 然后在代码中引用 imageView 和scrollView 的出口。
5 - 在viewDidLoad中,插入
self.automaticallyAdjustsScrollViewInsets = false 并设置scrollView的 contentInsets 和 contentOffset :
class ViewController: UIViewController {
@IBOutlet weak var scrollView: UIScrollView!
@IBOutlet weak var imageView: UIImageView!
override func viewDidLoad() {
super.viewDidLoad()
self.automaticallyAdjustsScrollViewInsets = false
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
let imageHeight = imageView.frame.height
let newOrigin = CGPoint(x: 0, y: -imageHeight)
scrollView.contentOffset = newOrigin
scrollView.contentInset = UIEdgeInsets(top: imageHeight, left: 0, bottom: 0, right: 0)
}
}
6 - 将scrollviewDelegate添加到ViewController和scrollViewDidScroll方法以获取scrollView的位置
class ViewController: UIViewController, UIScrollViewDelegate
override func viewDidLoad() {
super.viewDidLoad()
scrollView.delegate = self
self.automaticallyAdjustsScrollViewInsets = false
}
func scrollViewDidScroll(scrollView: UIScrollView) {
let offsetY = scrollView.contentOffset.y
if offsetY < 0
{
imageView.frame.size.height = -offsetY
}
else
{
imageView.frame.size.height = imageView.frame.height
}
}
7 - 然后构建并运行。
你可以在github上下载示例:https://github.com/raphrel/scalingImageWhenScrollDown
也许有更好的解决方案,但这个可行。
享受