I always keep those in my Constants.h file:
#define IS_IPHONE5 (([[UIScreen mainScreen] bounds].size.height-568)?NO:YES)
#define IS_OS_5_OR_LATER ([[[UIDevice currentDevice] systemVersion] floatValue] >= 5.0)
#define IS_OS_6_OR_LATER ([[[UIDevice currentDevice] systemVersion] floatValue] >= 6.0)
#define IS_OS_7_OR_LATER ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0)
#define IS_OS_8_OR_LATER ([[[UIDevice currentDevice] systemVersion] floatValue] >= 8.0)
#define IS_OS_9_OR_LATER ([[[UIDevice currentDevice] systemVersion] floatValue] >= 9.0)
Although I’ll always prefer the above macros, for the completion of the accepted answer, here is the apple approved way:
if (NSFoundationVersionNumber > NSFoundationVersionNumber_iOS_6_1) {
// do stuff for iOS 7 and newer
}
else {
// do stuff for older versions than iOS 7
}