iOS7 UITextView 光标问题

 1 -(void)textViewDidChange:(UITextView *)textView {
 2     CGRect line = [textView caretRectForPosition:
 3                    textView.selectedTextRange.start];
 4     CGFloat overflow = line.origin.y + line.size.height
 5     - ( textView.contentOffset.y + textView.bounds.size.height
 6        - textView.contentInset.bottom - textView.contentInset.top );
 7     if ( overflow > 0 ) {
 8         // We are at the bottom of the visible text and introduced a line feed, scroll down (iOS 7 does not do it)
 9         // Scroll caret to visible area
10         CGPoint offset = textView.contentOffset;
11         offset.y += overflow + 7; // leave 7 pixels margin
12         // Cannot animate with setContentOffset:animated: or caret will not appear
13         [UIView animateWithDuration:.2 animations:^{
14             [textView setContentOffset:offset];
15         }];
16     }
17 }