A bit late, but I had the same problem when resizing a uitextview and I think this is due to scrolling text view. This is my code that has 0 failures when animating height. I am using NSLayoutConstraint to adapt my height.
- (void)textViewDidChange:(UITextView *)textView { CGSize size = [messageView sizeThatFits:CGSizeMake(messageView.frame.size.width, FLT_MAX)]; [UIView animateWithDuration:0.4f animations:^{ messageHeightConstraint.constant = size.height; [self.view layoutIfNeeded]; } completion:^(BOOL finished) { [messageView scrollRangeToVisible:NSMakeRange([messageView.text length], 0)]; } ]; }
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