以编程方式将UIScrollView滚动到Swift中的子UIView（子视图）的顶部 [英] Programmatically scroll a UIScrollView to the top of a child UIView (subview) in Swift

问题描述

我的UIScrollView中有几个屏幕内容只能垂直滚动。

I have a few screens worth of content within my UIScrollView which only scrolls vertically.

我想以编程方式滚动到包含在其层次结构中的某个视图。

I want to programmatically scroll to a view contained somewhere in it's hierarchy.

UIScrollView移动，以便子视图位于UIScrollView的顶部（动画与否）

The UIScrollView move so that the child view is at the top of the UIScrollView (either animated or not)

推荐答案

这是我最后写的扩展。

用法：

从我的viewController调用，self.scrollView是UIScrollView的一个出口，self.commentsHeader是其中的一个视图，靠近底部：

Called from my viewController, self.scrollView is an outlet to the UIScrollView and self.commentsHeader is a view within it, near the bottom:

self.scrollView.scrollToView(self.commentsHeader, animated: true)

代码：

您只需要 scrollToView 方法，但留在 scrollToBottom / scrollToTop 方法，因为你可能也需要它们，但随意删除它们。

You only need the scrollToView method, but leaving in scrollToBottom / scrollToTop methods too as you'll probably need those too, but feel free to delete them.

extension UIScrollView {

    // Scroll to a specific view so that it's top is at the top our scrollview
    func scrollToView(view:UIView, animated: Bool) {
        if let origin = view.superview {
            // Get the Y position of your child view
            let childStartPoint = origin.convertPoint(view.frame.origin, toView: self)
            // Scroll to a rectangle starting at the Y of your subview, with a height of the scrollview
            self.scrollRectToVisible(CGRect(x:0, y:childStartPoint.y,width: 1,height: self.frame.height), animated: animated)
        }
    }

    // Bonus: Scroll to top
    func scrollToTop(animated: Bool) {
        let topOffset = CGPoint(x: 0, y: -contentInset.top)
        setContentOffset(topOffset, animated: animated)
    }

    // Bonus: Scroll to bottom
    func scrollToBottom() {
        let bottomOffset = CGPoint(x: 0, y: contentSize.height - bounds.size.height + contentInset.bottom)
        if(bottomOffset.y > 0) {
            setContentOffset(bottomOffset, animated: true)
        }
    }

}

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