Binary rejected for use of private API "transform:" in GDTCORTransformer

[steveshepard]

[REQUIRED] Step 1: Describe your environment

• Xcode version: 11.4.1
• Firebase SDK version: 6.24.0
• Firebase Component: GoogleDataTransport
• Component version: 6.1.0
• Installation method: CocoaPods

[REQUIRED] Step 2: Describe the problem

Apple rejected a binary built with the Firebase SDK.

Steps to reproduce:

1. Compile and link with the SDK.

2. Submit the binary for review.

3. Receive a rejection for using the private API "transform:"

Relevant Code:

The following code from GDTCORTransformer is the culprit:

      if ([transformer respondsToSelector:@selector(transform:)]) {
        GDTCORLogDebug(@"Applying a transformer to event %@", event);
        transformedEvent = [transformer transform:transformedEvent];
        if (!transformedEvent) {
          completion(NO, nil);
          return;
        }
      } else {
        GDTCORLogError(GDTCORMCETransformerDoesntImplementTransform,
                       @"Transformer doesn't implement transform: %@", transformer);
        completion(NO, nil);
        return;
      }

The transform: method doesn't seem to be implemented anywhere in the SDK. Is this, in fact, using private API?

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[morganchen12]

This seems like a false positive auto-reject from the App Store scanner. @steveshepard can you try appealing your app's rejection with the note that transform: in this case is a selector declared by a public Firebase dependency and not a private API?

[steveshepard]

Not sure if that will suffice given this:

"If method names in your source code match the private Apple APIs listed above, altering your method names will help prevent this app from being flagged in future submissions. In addition, note that one or more of the above APIs may be located in a static library that was included with your app. If so, they must be removed. For further information, visit the Technical Support Information at http://developer.apple.com/support/technical/"

[steveshepard]

Can you point me to the legit transform: implementation? Renaming that, at least temporarily, would also solve the problem.

[mikehaney24]

The header declaration is here: https://github.com/firebase/firebase-ios-sdk/blob/master/GoogleDataTransport/GDTCORLibrary/Public/GDTCOREventTransformer.h

This seems like a false positive rejection, I'd try appealing to Apple. Thousands of apps have shipped using these APIs. We'll try to see if there's anything we can do to help on our end.

[steveshepard]

Hi @mikehaney24,

Thanks for the reply. Yes, I saw the interface. I didn't see an implementation in the SDK though, which made me wonder.

I did submit another build this morning and it wasn't flagged, so perhaps this rejection was the result of a new check they rolled back. Hard to believe that there aren't tons of apps that declare a "transform:" method.

[mikehaney24]

Indeed, -transform seems like probably a common method. Thanks for following up to let us know!