iOS unique user identifier [duplicate]

Question

I'm writting an application for iphone, which communicates with my server using REST. The main problem is, I need to identify user somehow. Not so long ago, we were allowed to use UDID, but now its not allowed anymore. So what should I use instead? I need some kind of identifier on iphone, so user will delete application, install it again, and he will get same id.

Answer 1

I used CFUUIDCreate() to create a UUID:

+ (NSString *)GetUUID {   CFUUIDRef theUUID = CFUUIDCreate(NULL);   CFStringRef string = CFUUIDCreateString(NULL, theUUID);   CFRelease(theUUID);   return [(NSString *)string autorelease]; } 

Then set the above UUID to my NSString:

NSString *UUID = [nameofclasswhereGetUUIDclassmethodresides UUID]; 

I then stored that UUID to the Keychain using SSKeyChain

To set the UUID with SSKeyChain:

[SSKeychain setPassword:UUID forService:@"com.yourapp.yourcompany" account:@"user"]; 

To Retrieve it:

NSString *retrieveuuid = [SSKeychain passwordForService:@"com.yourapp.yourcompany" account:@"user"]; 

When you set the UUID to the Keychain, it will persist even if the user completely uninstalls the App and then installs it again.

To make sure ALL devices have the same UUID in the Keychain.

1. Setup your app to use iCloud.
2. Save the UUID that is in the Keychain to NSUserDefaults as well.
3. Pass the UUID in NSUserDefaults to the Cloud with Key-Value Data Store.
4. On App first run, Check if the Cloud Data is available and set the UUID in the Keychain on the New Device.

You now have a Unique Identifier that is persistent and shared/synced with all devices.