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iosuiscrollviewuitextview
Bartosz Bialecki
Bartosz Bialecki

Reputation: 4451

iOS: Scroll view to the current cursor position in text view

I have UIScrollView which has some views including UITextView. UITextView is bigger that the screen and has some text and has scrolling disabled. If the user tap on text view I would like to scroll my main scroll view to the position of the cursor in the text view. How can I do it? I tried use selectedRange but it doesn't seem to work.

Upvotes: 2

Views: 2172

Answers (2)

Valentin Shergin
Valentin Shergin

Reputation: 7344

Here is my a little more sofisticated solution:

- (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];
}

Upvotes: 1

Bartosz Bialecki
Bartosz Bialecki

Reputation: 4451

I did it in such way:

- (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];
}

if someone knows the better solution then please write the answer and I will accept it.

Upvotes: 0

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