contentOffset Changes when Setting UITextView Frame in textViewDidChange

Question

I am trying to set the height of a UITextView dynamically in textViewDidChange. I get the frame to adjust to the proper height, but when the height is greater than a threshold that I have set, then the textView should just scroll with a new line. However, the contentOffset gets messed up and it doesn't scroll down to fully include the new line.

- (void)viewDidLoad
{
    [super viewDidLoad];
    _textView.frame = CGRectMake(60, 100, 200, _textView.contentSize.height);
    _textView.scrollEnabled = NO;
}

- (void)textViewDidChange:(UITextView *)textView
{
    NSLog(@"Offset: %f", _textView.contentOffset.y);

    CGFloat height = _textView.contentSize.height;
    _textView.scrollEnabled = NO;

    if (_textView.contentSize.height >= 120) {
        height = 120;
        _textView.scrollEnabled = YES;
        _textView.contentOffset = CGPointMake(0, _textView.contentSize.height - _textView.frame.size.height);
    }

    CGRect frame = _textView.frame;
    frame.size.height = height;
    _textView.frame = frame;
}

I suppose an easier way of explaining what is happening is this. On a completely blank view controller add a UITextView in Storyboard. Then add only these three lines into textViewDidChange:

CGRect frame = _textView.frame;
frame.size.height = _textView.contentSize.height;
_textView.frame = frame;

Every other time the textView's height increases, the text is not vertically centered. If you scroll it around though and then let go it will return to the correct position. The frame is always the correct size. It is the contentOffset that is not quite right.

user352891 user352891 · Accepted Answer · 2013-04-06T22:32:25

I wonder if you could post some code as to what you're actually doing?

I've just tried this on 5.0 and this works.

-(void) textViewDidChange:(UITextView *)textView {
int maxHeight = 30;
CGFloat height = [textView.text sizeWithFont:textView.font constrainedToSize:CGSizeMake(textView.frame.size.width, 99999) lineBreakMode:NSLineBreakByWordWrapping].height;

CGRect rect = textView.frame;
rect.size.height = MIN(height, maxHeight);
[textView setFrame:rect];

}

contentOffset Changes when Setting UITextView Frame in textViewDidChange

1 Answers