func randomUUID() -> NSString{ return NSUUID.UUID().UUIDString()}
+ (NSString *)randomUUID { if(NSClassFromString(@"NSUUID")) { // only available in iOS >= 6.0 return [[NSUUID UUID] UUIDString]; } CFUUIDRef uuidRef = CFUUIDCreate(kCFAllocatorDefault); CFStringRef cfuuid = CFUUIDCreateString(kCFAllocatorDefault, uuidRef); CFRelease(uuidRef); NSString *uuid = [((__bridge NSString *) cfuuid) copy]; CFRelease(cfuuid); return uuid; }