ASIdentifierManager API.

This API is expected to be used by developers who are implementing a system for serving ads. Typically these organizations provide app developers with the code that interacts with this class. 
In order to get advertisingIdentifier and  advertisingTrackingEnabled you need to use SharedManager - a shared instance of the ISN_ASIdentifierManager class.

Advertising Tracking

Check whether advertising tracking is limited using the advertisingTrackingEnabled  property.

ISN_ASIdentifierManager.SharedManager.AdvertisingTrackingEnabled

Advertising Identifier

Get the advertising identifier using the advertisingIdentifier property (note that when ad tracking is limited, the value of the advertising identifier is 00000000-0000-0000-0000-000000000000).

ISN_ASIdentifierManager.SharedManager.AdvertisingIdentifier
Unlike the identifierForVendor property of the UIDevice, the same value is returned to all vendors. This identifier may change—for example, if the user erases the device—so you should not cache it.