UDID替代方案

   //使用KeychainItemWrapper工具类，将生成的UUID保存在iOS系统的KeyChain+ (NSString *)UUID { KeychainItemWrapper *keyChainWrapper = [[KeychainItemWrapper alloc] initWithIdentifier:@"MYAppID" accessGroup:@"com.test.app"]; NSString *UUID = [keyChainWrapper objectForKey:(__bridge id)kSecValueData]; if (UUID == nil || UUID.length == 0) { UUID = [[[UIDevice currentDevice] identifierForVendor] UUIDString]; [keyChainWrapper setObject:UUID forKey:(__bridge id)kSecValueData]; } return UUID;}