The Apple App Store has begun stricter enforcement of the use of IDFA (identifier for advertising). Apps that use IDFA but do not serve ads may be rejected from the App Store during the submission process.
The Socialize iOS SDK and its dependent libraries make use of IDFA for tracking and analytics. Effective with release 3.0.3 of the SDK, references to IDFA can be removed before app/SDK compilation via a C-style preprocessor directive. This is necessary as any references to “advertisingIdentifier” in the compiled app will trigger a rejection if the app being submitted does not serve ads.
This change must be made in source files before compiling any apps that use the Socialize iOS SDK. Since the SDK and its dependent libraries are now distributed as CocoaPods, this step must be done in the source files located in the “Pods” project of your app’s Xcode workspace; it can also be done in repos forked or downloaded and included in your project/workspace. For more information, see the following documentation pages:
Note that IDFA enablement/disablement can only be done in source files before compilation. You can make these changes in CocoaPods source or downloaded source, but cannot do so from the SDK’s .embeddedFramework package. If you are still using the .embeddedFramework and need to make this IDFA change, you must begin using CocoaPods or fork/download source from GitHub.
More information here.