Vertically and horizontally centering the contents of a UILabel, with dynamic text and font size, within a given CGRect. This can be used, for example, to draw numbers within a container, like a small circle, since the size of the text of a number is difficult to predict.

centerLabelInRect.m

//Note, this should probably be handled in a different way in production code
#define MIN_FONT_SIZE 3.25f
 
- (void)label:(UILabel*)label setText:(NSString*)text andCenterInRect:(CGRect)rect {
    label.text = [NSString stringWithFormat:@"%d", indicatorNumber];
    
    CGFloat fontSizeOfContents;
    [label.text sizeWithFont:label.font
                 minFontSize:MIN_FONT_SIZE
              actualFontSize:&fontSizeOfContents
                    forWidth:rect.size.width
               lineBreakMode:NSLineBreakByWordWrapping];
    
    label.font = [UIFont systemFontOfSize:fontSizeOfContents];
    [label sizeToFit];
    
    label.center = CGPointMake(rect.size.width / 2.0f, rect.size.height / 2.0f);
}