失去UUID
得到UUID
+ (NSString *)makeUUID {
CFUUIDRef uuidRef = CFUUIDCreate(NULL);
CFStringRef uuidStringRef = CFUUIDCreateString(NULL, uuidRef);
CFRelease(uuidRef);
NSString* uuid = [NSString stringWithString:(NSString *)uuidStringRef];
CFRelease(uuidStringRef);
return uuid;
}