In an iPhone app I'm working on, I'm trying to get a UILabel to dynamically adjust its size based on its content. To do so, I'm using NSString's sizeWithFont:constrainedToSize method to measure the height of the text when constrained to a given width, and then set the UILabel to that width and the returned height. The problem however, is that roughly half the time sizeWithFont is returning a height for the text that is one line too short. This happens mostly with long strings (a couple of hundred characters), but also very occasionally with shorter strings (less than one hundred).

For reference, my code looks like the following (textLabel is the UILabel in question and is a member variable, TEXT_WIDTH is the desired label width):

- (void) setLabelText:(NSString*) text
{
    CGSize bounds = CGSizeMake(TEXT_WIDTH, CGFLOAT_MAX);
    int textHeight = [text sizeWithFont:textLabel constrainedToSize:bounds
        lineBreakMode:UILineBreakModeWordWrap].height;
    CGRect newFrame = CGRectMake(0, 0, TEXT_WIDTH, textHeight);

    [textLabel setFrame:newFrame];
}

Just to be clear, I don't believe the issue is with the UILabel, as I've manually inspected the value being returned by sizeWithFont and can confirm that the number being returned for the height is too small on the occasions when the label is also too small.