How to measure text on both iPhone and OSX (sizeWithFont for OSX)

gistfile1.m

// Part of a category on NSString...
- (CGSize)sizeWithFontName:(NSString*)fontName ofSize:(float)size constrainedTo:(CGSize)constraint {
#ifdef __CC_PLATFORM_MAC
  NSFont *font = [NSFont fontWithName:fontName size:size];
  
  NSTextStorage *textStorage = [[NSTextStorage alloc] initWithString:self];
  NSTextContainer *textContainer = [[NSTextContainer alloc] initWithContainerSize:constraint];
  ;
  NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
  [layoutManager addTextContainer:textContainer];
  [textStorage addLayoutManager:layoutManager];
  [textStorage addAttribute:NSFontAttributeName value:font
                      range:NSMakeRange(0, [textStorage length])];
  [textContainer setLineFragmentPadding:0.0];
  
  (void) [layoutManager glyphRangeForTextContainer:textContainer];
  return [layoutManager
          usedRectForTextContainer:textContainer].size;
#elif defined(__CC_PLATFORM_IOS)
  UIFont * font = [UIFont fontWithName:fontName size:size];
  return [self sizeWithFont:font constrainedToSize:constraint lineBreakMode:NSLineBreakByWordWrapping];
#endif
  return CGSizeZero;
}