以编程方式设置文本时停止跳转UITextView

Question

我必须在滚动的UITextView中更新少量文本.我只会插入光标当前所在的字符,我只需按一下导航栏上的按钮即可.

我的问题是每当我调用文本视图的setText方法时,它都会跳转到文本的底部.我已经尝试使用contentOffset并重置selectedRange但它不起作用!这是我的例子:

// Remember offset and selection
CGPoint contentOffset = [entryTextView contentOffset];
NSRange selectedRange = [entryTextView selectedRange];
// Update text
entryTextView.text = entryTextView.text;
// Try and reset offset and selection
[entryTextView setContentOffset:contentOffset animated:NO];
[entryTextView setSelectedRange: selectedRange];

有没有办法可以在没有任何滚动动作的情况下更新文本...好像他们只是在键盘上输入了一些东西？

编辑:

我已经尝试使用textViewDidChange:delegate方法,但它仍然没有滚动到原始位置.

- (void)textViewDidChange:(UITextView *)textView {
    if (self.programChanged) {
        [textView setSelectedRange:self.selectedRange];
        [textView setContentOffset:self.contentOffset animated:NO];
        self.programChanged = NO;
    }
}

- (void)changeButtonPressed:(id)sender {
    // Remember position
    self.programChanged = YES;
    self.contentOffset = [entryTextView contentOffset];
    self.selectedRange = [entryTextView selectedRange];
    // Update text
    entryTextView.text = entryTextView.text;
}

Answer 1

如果您使用iPhone 3.0或更高版本,则可以解决此问题:

textView.scrollEnabled = NO;

//You should know where the cursor will be(if you update your text by appending/inserting/deleting you can know the selected range) so keep it in a NSRange variable.

Then update text:
textView.text = yourText;

textView.scrollEnabled = YES;
textView.selectedRange = range;//you keep before

它现在应该工作(不再跳跃)

关心Meir Assayag

Answer 2

基于Meir的建议,这里的代码以编程方式删除选择(是的,我知道有一个选择菜单按钮也可以,但我做的事情有点时髦)而不滚动文本视图.

NSRange selectedRange = textView.selectedRange;
textView.scrollEnabled = NO;
// I'm deleting text. Replace this line with whatever insertions/changes you want
textView.text = [textView.text
                stringByReplacingCharactersInRange:selectedRange withString:@""];
selectedRange.length = 0;
// If you're inserting text, you might want to increment selectedRange.location to be
// after the text you inserted
textView.selectedRange = selectedRange;
textView.scrollEnabled = YES;

Answer 3

此决定适用于iOS 8:

let offset = textView.contentOffset
textView.text = newText
textView.layoutIfNeeded()
textView.setContentOffset(offset, animated: false)

有必要完全调用,setContentOffset:animated:因为只有这将取消动画.textView.contentOffset = offset不会取消动画,也无济于事.

Answer 4

看看 UITextViewDelegate，我相信 textViewDidChangeSelection 方法可以让您做您需要的事情。