ios 获取 UIScrollView 滚动到顶部
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Get UIScrollView to scroll to the top
提问by Hyman Humphries
How do I make a UIScrollView scroll to the top?
如何让 UIScrollView 滚动到顶部？
回答by rob mayoff
UPDATE FOR iOS 7
iOS 7 更新
[self.scrollView setContentOffset:
CGPointMake(0, -self.scrollView.contentInset.top) animated:YES];
ORIGINAL
原来的
[self.scrollView setContentOffset:CGPointZero animated:YES];
or if you want to preserve the horizontal scroll position and just reset the vertical position:
或者，如果您想保留水平滚动位置并重置垂直位置：
[self.scrollView setContentOffset:CGPointMake(self.scrollView.contentOffset.x, 0)
animated:YES];
回答by Andrew Schreiber
Here is a Swift extension that makes it easy:
这是一个 Swift 扩展，它使它变得容易：
extension UIScrollView {
func scrollToTop() {
let desiredOffset = CGPoint(x: 0, y: -contentInset.top)
setContentOffset(desiredOffset, animated: true)
}
}
Usage:
用法：
myScrollView.scrollToTop()
回答by Rajasekhar Pasupuleti
For Swift 4
对于 Swift 4
scrollView.setContentOffset(.zero, animated: true)
回答by Jakub Truhlá?
iOS 11 and above
iOS 11 及以上
try to work with the new adjustedContentInset.
尝试使用新的adjustedContentInset.
For example (scroll to the top):
例如（滚动到顶部）：
var offset = CGPoint(
x: -scrollView.contentInset.left,
y: -scrollView.contentInset.top)
if #available(iOS 11.0, *) {
offset = CGPoint(
x: -scrollView.adjustedContentInset.left,
y: -scrollView.adjustedContentInset.top)
}
scrollView.setContentOffset(offset, animated: true)
Even if you use
prefersLargeTitles,safe areaetc.
即使你使用
prefersLargeTitles，safe area等等。
回答by Bryan Chen
Use setContentOffset:animated:
用 setContentOffset:animated:
[scrollView setContentOffset:CGPointZero animated:YES];
回答by worthbak
Answer for Swift 2.0/3.0/4.0 and iOS 7+:
Swift 2.0/3.0/4.0 和 iOS 7+ 的答案：
let desiredOffset = CGPoint(x: 0, y: -self.scrollView.contentInset.top)
self.scrollView.setContentOffset(desiredOffset, animated: true)
回答by hoak
In iOS7 I had trouble getting a particular scrollview to go to the top, which worked in iOS6, and used this to set the scrollview to go to the top.
在 iOS7 中，我无法让特定的滚动视图转到顶部，这在 iOS6 中有效，并使用它来设置滚动视图转到顶部。
[self.myScroller scrollRectToVisible:CGRectMake(0, 0, 1, 1) animated:NO];
回答by Roni Leshes
Swift 3.0.1 version of rob mayoff's answer:
Swift 3.0.1 版本的rob mayoff 的回答：
self.scrollView.setContentOffset(
CGPoint(x: 0,y: -self.scrollView.contentInset.top),
animated: true)
回答by user2898617
I think I have an answer that should be fully compatible with iOS 11 as well as prior versions (for vertical scrolling)
我想我的答案应该与 iOS 11 以及之前的版本完全兼容（用于垂直滚动）
This takes into account the new adjustedContentInsetand also accounts for the additional offset required when prefersLargeTitlesis enabled on the navigationBar which appears to require an extra 52px offset on top of whatever the default is
这考虑了新的adjustedContentInset并考虑了在导航栏上启用prefersLargeTitles时所需的额外偏移量，这似乎需要在默认值之上额外的52px 偏移量
This was a little tricky because the adjustedContentInset changes depending on the titleBar state (large title vs small title) so I needed to check and see what the titleBar height was and not apply the 52px offset if its already in the large state. Couldn't find any other method to check the state of the navigationBar so if anyone has a better option than seeing if the height is > 44.0 I'd like to hear it
这有点棘手，因为adjustedContentInset 根据titleBar 状态（大标题与小标题）而变化，所以我需要检查并查看titleBar 高度是多少，如果它已经处于大状态，则不应用52px 偏移量。找不到任何其他方法来检查导航栏的状态，所以如果有人有比查看高度是否 > 44.0 更好的选择，我想听听
func scrollToTop(_ scrollView: UIScrollView, animated: Bool = true) {
if #available(iOS 11.0, *) {
let expandedBar = (navigationController?.navigationBar.frame.height ?? 64.0 > 44.0)
let largeTitles = (navigationController?.navigationBar.prefersLargeTitles) ?? false
let offset: CGFloat = (largeTitles && !expandedBar) ? 52: 0
scrollView.setContentOffset(CGPoint(x: 0, y: -(scrollView.adjustedContentInset.top + offset)), animated: animated)
} else {
scrollView.setContentOffset(CGPoint(x: 0, y: -scrollView.contentInset.top), animated: animated)
}
}
Inspired by Jakub's solution
灵感来自 Jakub 的解决方案
回答by Vitya Shurapov
It's very common when your navigation bar overlapsthe small portion of the scrollView content and it looks like content starts not from the top. For fixing it I did 2 things:
当您的导航栏与scrollView 内容的一小部分重叠并且看起来内容不是从顶部开始时，这是很常见的。为了修复它，我做了两件事：
- Size Inspector - Scroll View - Content Insets --> Change from Automatic to Never.
- Size Inspector - Constraints- "Align Top to" (Top Alignment Constraints)- Second item --> Change from Superview.Top to Safe Area.Topand the value(constant field) set to 0
- 尺寸检查器 - 滚动视图 -内容插入 --> 从自动更改为从不。
- Size Inspector - Constraints- "Align Top to" (Top Alignment Constraints)- 第二项 -->从 Superview.Top 更改为 Safe Area.Top并将值（常量字段）设置为 0
