iOS platform Udid scenario comparison

Apple disabled [Uidevice uniqueidentifier] in iOS6, and the MAC address was blocked in the iOS7. No way, after all, they are the eldest, said not to let you use, you have no way.
Here is a summary of the existing part of the Udid acquisition method (Apple-recommended, also has a third-party), the purpose is to throw bricks, there is no real explanation of which method to use. It is entirely up to you to decide which method to use.

Ios2~ios7 Current Technical Solutions

System support situation
After iOS6, Apple has disabled the Uidevice uniqueidentifier method, so the traditional Udid method can not be used after iOS6, and from the IOS7, the method to obtain the MAC address unified return 02:0 0:00:00:00:00, so using the Mac+md5 method is meaningless.

Persistence situation

Note:

√ Indicates that the UDID can be guaranteed to persist, x indicates that Udid may lose the change in this case, and that the situation is not actually verified, purely speculative (after all, upgrading the system or something too cumbersome) pros and cons

iOS platform Udid scenario comparison