根据@moonlight提出的链接，我做了几次测试，这似乎是最好的解决方案。正如@DarkDust所说，该方法将检查始终可用的en0。 有两种选择: uniqueDeviceIdentifier (MAC+CFBundleIdentifier的MD5) 和uniqueGlobalDeviceIdentifier(MAC的MD5)，这些总是返回相同的值。 下面是我所做的测试(用真正的设备):

#import "UIDevice+IdentifierAddition.h"

NSLog(@"%@",[[UIDevice currentDevice] uniqueDeviceIdentifier]);
NSLog(@"%@",[[UIDevice currentDevice] uniqueGlobalDeviceIdentifier]);

XXXX21f1f19edff198e2a2356bf4XXXX - (WIFI)UDID XXXX7dc3c577446a2bcbd77935bdXXXX - (WIFI)GlobalAppUDID XXXX21f1f19edff198e2a2356bf4XXXX - (3G)UDID XXXX7dc3c577446a2bcbd77935bdXXXX - (3G)GlobalAppUDID XXXX21f1f19edff198e2a2356bf4XXXX - (GPRS)UDID XXXX7dc3c577446a2bcbd77935bdXXXX - (GPRS)GlobalAppUDID XXXX21f1f19edff198e2a2356bf4XXXX - (AirPlane mode)UDID XXXX7dc3c577446a2bcbd77935bdXXXX - (AirPlane mode)GlobalAppUDID XXXX21f1f19edff198e2a2356bf4XXXX - (Wi-Fi)after removing and reinstalling the app XXXX7dc3c577446a2bcbd77935bdXXXX (Wi-Fi) after removing and installing the app

希望对大家有用。

编辑: 正如其他人指出的那样，这个解决方案在iOS 7中不再有用，因为uniqueIdentifier不再可用，查询MAC地址现在总是返回02:00:00:00:00:00

虽然不完美，但却是UDID的最佳和最接近的替代品之一(在Swift中使用iOS 8.1和Xcode 6.1):

生成一个随机UUID

let strUUID: String = NSUUID().UUIDString

并使用KeychainWrapper库:

给keychain添加一个字符串值:

let saveSuccessful: Bool = KeychainWrapper.setString("Some String", forKey: "myKey")

从keychain中检索字符串值:

let retrievedString: String? = KeychainWrapper.stringForKey("myKey")

从keychain中删除一个字符串值:

let removeSuccessful: Bool = KeychainWrapper.removeObjectForKey("myKey")

该解决方案使用了keychain，因此存储在keychain中的记录将被持久化，即使在应用程序卸载和重新安装之后。删除该记录的唯一方法是重置设备的所有内容和设置。这就是为什么我提到这个替代方案并不完美，但仍然是iOS 8.1上使用Swift替代UDID的最佳方案之一。

MAC地址可以被欺骗，这使得这种方法对于将内容绑定到特定用户或实现黑名单等安全功能毫无用处。

经过一些进一步的研究，在我看来，我们现在没有一个合适的替代方案。我真心希望苹果能重新考虑他们的决定。

也许给苹果发邮件讨论这个话题是个好主意，或者提交一个关于这个问题的bug /功能请求，因为他们可能还没有意识到这对开发者的全部后果。

我也遇到了一些问题，解决方法很简单:

    // Get Bundle Info for Remote Registration (handy if you have more than one app)
    NSString *appName = [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleDisplayName"];
    NSString *appVersion = [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleVersion"];


    // Get the users Device Model, Display Name, Unique ID, Token & Version Number
    UIDevice *dev = [UIDevice currentDevice];
    NSString *deviceUuid=[dev.identifierForVendor  UUIDString];

    NSString *deviceName = dev.name;

下面的代码有助于获得UDID:

        udid = [[[UIDevice currentDevice] identifierForVendor] UUIDString];
        NSLog(@"UDID : %@", udid);

我相信苹果公司的这一变化惹恼了很多人。我开发了一个iOS的簿记应用程序，并有一个在线服务来同步不同设备上的更改。该服务维护所有设备的数据库以及需要传播到这些设备的更改。因此，了解哪种设备是哪种设备很重要。我使用UIDevice uniqueIdentifier跟踪设备，为了它的价值，这里是我的想法。

Generate a UUID and store in user defaults? No good because this does not persist when the user deletes the app. If they install again later the online service should not create a new device record, that would waste resources on the server and give a list of devices containing the same one two or more times. Users would see more than one "Bob's iPhone" listed if they re-installed the app. Generate a UUID and store in the keychain? This was my plan, since it persists even when the app is uninstalled. But when restoring an iTunes backup to a new iOS device, the keychain is transferred if the backup is encrypted. This could lead to two devices containing the same device id if the old and new devices are both in service. These should be listed as two devices in the online service, even if the device name is the same. Generate a hash the MAC address and bundle id? This looks like the best solution for what I need. By hashing with the bundle id, the generated device id is not going to enable the device to be tracked across apps and I get a unique ID for the app+device combination.

有趣的是，苹果自己的文档提到通过计算系统Mac地址加上bundle id和版本的哈希来验证Mac App Store收据。所以这似乎是政策允许的，但是否通过应用审查我还不知道。