iOS：滚动视图到文本视图中的当前光标位置

Posted 2023-02-24

【中文标题】iOS：滚动视图到文本视图中的当前光标位置

【英文标题】：iOS: Scroll view to the current cursor position in text view

【发布时间】：2014-04-16 13:34:26

【问题描述】：

我有 UIScrollView，它有一些视图，包括 UITextView。 UITextView 比屏幕大，有一些文本，并且禁用了滚动。如果用户点击文本视图，我想将我的主滚动视图滚动到文本视图中光标的位置。我该怎么做？我尝试使用 selectedRange 但它似乎不起作用。

【参考方案1】：

这是我的一个更复杂的解决方案：

- (void)scrollView:(UIScrollView *)scrollView scrollToTextInput:(UIResponder *)responder

    if (!responder || ![responder conformsToProtocol:@protocol(UITextInput)] || ![responder isKindOfClass:[UIView class]]) 
        return;
    

    UIView<UITextInput> *textInput = (UIView<UITextInput> *)responder;

    UIView *nextView = textInput;
    while (nextView && (nextView != scrollView))
    
        nextView = [nextView superview];
    

    if (!nextView)
    
        // Oh, this view is not from our `scrollView`.
        return;
    

    CGRect cursorRect = [textInput caretRectForPosition:textInput.selectedTextRange.start];
    CGPoint cursorPoint = CGPointMake(CGRectGetMidX(cursorRect), CGRectGetMidY(cursorRect));
    cursorPoint = [scrollView convertPoint:cursorPoint fromView:textInput];

    CGFloat contentHeight = scrollView.contentSize.height;
    CGFloat containerHeight = scrollView.frame.size.height;
    CGFloat topInset = scrollView.contentInset.top;
    CGFloat bottomInset = scrollView.contentInset.bottom;
    CGFloat verticalInsets = scrollView.contentInset.top + scrollView.contentInset.bottom;

    CGFloat offsetY = cursorPoint.y - (containerHeight - verticalInsets) / 2.f;
    offsetY = MIN(MAX(offsetY, topInset), contentHeight - containerHeight + verticalInsets);

    [scrollView setContentOffset:CGPointMake(scrollView.contentOffset.x, offsetY) animated:YES];

【参考方案2】：

我是这样做的：

- (void)textViewDidBeginEditing:(UITextView *)textView

     [self performSelector:@selector(scrollToCursorPosition:) withObject:textView afterDelay:0.05f];


- (void)scrollToCursorPosition:(UITextView *)textView

    UITextRange *range = textView.selectedTextRange;
    UITextPosition *position = range.start;
    CGRect cursorRect = [textView caretRectForPosition:position];
    CGPoint cursorPoint = CGPointMake(textView.frame.origin.x + cursorRect.origin.x, textView.frame.origin.y + cursorRect.origin.y);
    [self setContentOffset:CGPointMake((cursorPoint.x - 10) * self.zoomScale, (cursorPoint.y - 10) * self.zoomScale) animated:NO];

如果有人知道更好的解决方案，请写下答案，我会接受。