UILabel text size fit macro

// UILabel text size fit macro
//
// use :
//
// UILabel *label = ....
// TEXT_FIT(label, @"your text here");
//
#define SYSTEM_VERSION_LESS_THAN(v) ([[[UIDevice currentDevice] systemVersion] compare:v options:NSNumericSearch] == NSOrderedAscending)
#define TEXT_FIT_IOS6(t,txt)  (CGRect){t.frame.origin, t.frame.size.width, [txt sizeWithFont:t.font constrainedToSize:t.frame.size lineBreakMode:t.lineBreakMode].height}
#define TEXT_FIT_IOS7(t,txt) (CGRect){t.frame.origin, t.frame.size.width, [txt boundingRectWithSize:t.frame.size options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:t.font} context:nil].size.height}
#define TEXT_FIT(t,txt) {t.text = txt;t.numberOfLines = 0;t.frame = SYSTEM_VERSION_LESS_THAN(@"7.0")?TEXT_FIT_IOS6(t,txt):TEXT_FIT_IOS7(t,txt);}