ios 每次更改文本时，如何强制 UITextView 滚动到顶部？
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How do I force a UITextView to scroll to the top every time I change the text?
提问by Sam Stewart
OK, I'm having some problem with the UITextView. Here's the issue:
好的，我的UITextView. 这是问题：
I add some text to a UITextView. The user then double clicks to select something.
I then change the text in the UITextView(programatically as above) and the UITextViewscrolls to the bottom of the page where there is a cursor.
我将一些文本添加到UITextView. 然后用户双击以选择某些内容。然后我更改UITextView（以编程方式如上）中的文本，然后UITextView滚动到页面底部有光标的位置。
However, that is NOT where the user clicked. It ALWAYS scrolls to the bottom of the UITextViewregardless of where the user clicked.
然而，这不是用户点击的地方。UITextView无论用户点击哪里，它总是滚动到底部。
So here's my question: How do I force the UITextViewto scroll to the top every time I change the text? I've tried contentOffsetand scrollRangeToVisible. Neither work.
所以这是我的问题：UITextView每次更改文本时如何强制滚动到顶部？我试过contentOffset和scrollRangeToVisible。都不工作。
Any suggestions would be appreciated.
任何建议，将不胜感激。
回答by Wayne Lo
UITextView*note;
[note setContentOffset:CGPointZero animated:YES];
This does it for me.
这对我有用。
Swift version (Swift 4.1 with iOS 11 on Xcode 9.3):
Swift 版本（Xcode 9.3 上的 Swift 4.1 和 iOS 11）：
note.setContentOffset(.zero, animated: true)
回答by nerd2know
If anyone has this problem in iOS 8, I found that just setting the UITextView'stext property, then calling scrollRangeToVisiblewith an NSRangewith location:0, length:0, worked. My text view was not editable, and I tested both selectable and not selectable (neither setting affected the result). Here's a Swift example:
如果有人在 iOS 8 中遇到此问题，我发现只需设置UITextView'stext 属性，然后scrollRangeToVisible使用NSRangewith location:0,调用即可length:0。我的文本视图不可编辑，我测试了可选择和不可选择（两种设置都不会影响结果）。这是一个 Swift 示例：
myTextView.text = "Text that is long enough to scroll"
myTextView.scrollRangeToVisible(NSRange(location:0, length:0))
回答by miguel
And here is my solution...
这是我的解决方案......
override func viewDidLoad() {
textView.scrollEnabled = false
textView.text = "your text"
}
override func viewDidAppear(animated: Bool) {
textView.scrollEnabled = true
}
回答by RyanTCB
Calling
打电话
scrollRangeToVisible(NSMakeRange(0, 0))
works but call it in
工作，但调用它
override func viewDidAppear(animated: Bool)
回答by Maria
I was using attributedString in HTML with text view not editable. Setting the content offset did not work for me either. This worked for me: disable scroll enabled, set the text and then enable the scrolling again
我在 HTML 中使用了 attributedString，文本视图不可编辑。设置内容偏移对我也不起作用。这对我有用：禁用滚动启用，设置文本，然后再次启用滚动
[yourTextView setScrollEnabled:NO];
yourTextView.text = yourtext;
[yourTextView setScrollEnabled:YES];
回答by Drew S.
Since none of these solutions worked for me and I wasted way too much time piecing together solutions, this finally solved it for me.
由于这些解决方案都不适合我，而且我浪费了太多时间拼凑解决方案，这终于为我解决了。
override func viewWillAppear(animated: Bool) {
dispatch_async(dispatch_get_main_queue(), {
let desiredOffset = CGPoint(x: 0, y: -self.textView.contentInset.top)
self.textView.setContentOffset(desiredOffset, animated: false)
})
}
This is really silly that this is not default behavior for this control.
这不是此控件的默认行为，这真的很愚蠢。
I hope this helps someone else out.
我希望这可以帮助其他人。
回答by Benjamin Sussman
I'm not sure if I understand your question, but are you trying to simply scroll the view to the top? If so you should do
我不确定我是否理解您的问题，但是您是否想简单地将视图滚动到顶部？如果是这样你应该做
[textview scrollRectToVisible:CGRectMake(0,0,1,1) animated:YES];
[textview scrollRectToVisible:CGRectMake(0,0,1,1) animated:YES];
回答by ChallengerGuy
For iOS 10 and Swift 3 I did:
对于 iOS 10 和 Swift 3，我做了：
override func viewDidLoad() {
super.viewDidLoad()
textview.isScrollEnabled = false
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
textView.isScrollEnabled = true
}
Worked for me, not sure if you're having the problem with the latest version of Swift and iOS.
为我工作，不确定您是否在使用最新版本的 Swift 和 iOS 时遇到问题。
回答by MacInnis
I have an updated answer which will have the textview appear properly, and without the user experiencing a scroll animation.
我有一个更新的答案，它将使 textview 正确显示，并且没有用户体验滚动动画。
override func viewWillAppear(animated: Bool) {
dispatch_async(dispatch_get_main_queue(), {
self.introductionText.scrollRangeToVisible(NSMakeRange(0, 0))
})
回答by Maksym Horbenko
That's how I did it
我就是这样做的
Swift 4:
斯威夫特 4：
extension UITextView {
override open func draw(_ rect: CGRect)
{
super.draw(rect)
setContentOffset(CGPoint.zero, animated: false)
}
}
