问题描述
向下滚动时如何使用 autolayout 简单地缩放 imageView ?
How can I simply scaling imageView with autolayout when scrolling down ?
尝试查看视差效果,但不是我想要的.
Try to see parallax effect but not exactly what I wanted.
我只想使用一个 scrollView 和一个标题 ImageView 可以调整大小取决于 scrollView 位置.
I just want to use a scrollView and a header ImageView who can resize depends on scrollView position.
推荐答案
一步一步:
1 - 打开故事板并在顶部添加具有这些约束的图像视图(选择您的纵横比):
1 - open storyboard and add an image view on top with these constraint (choose your aspect ratio) :
2 - 为你的 uiimage 选择 aspectFill 模式和 clipSubviews
2 - select aspectFill mode and clipSubviews for your uiimage
3 - 在 vi??ewController 的顶部添加一个 UIScrollView,里面有一个子视图.有关使用 scrollView 的自动布局的所有详细信息:http://natashatherobot.com/ios-autolayout-scrollview/
3 - add a UIScrollView on top of your viewController with a child view inside. All the details about the auto layout with scrollView : http://natashatherobot.com/ios-autolayout-scrollview/
4 - 然后在代码中引用您的 imageView 和 scrollView.
4 - then make outlets reference of your imageView and scrollView in your code.
5 - 在 vi??ewDidLoad 中,插入self.automaticallyAdjustsScrollViewInsets = false 并设置 scrollView 的 contentInsets 和 contentOffset :
5 - in viewDidLoad, insert self.automaticallyAdjustsScrollViewInsets = false and set contentInsets and contentOffset of the scrollView :
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
6 - add scrollviewDelegate to the ViewController and the scrollViewDidScroll method to get position of the scrollView
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.
7 - then build and run.
您可以在 github 上下载示例:https://github.com/raphrel/scalingImageWhenScrollDown
you can download example on github: https://github.com/raphrel/scalingImageWhenScrollDown
也许有更好的解决方案,但这个可行.享受
there is maybe a better solution but this one works. enjoy