SIWA on iPadOS : identityToken can be null

[ttermeer-reboundcg]

Step 1: Are you in the right place?

The fault could be from FirebaseAuth

Step 2: Describe your environment

• Objective C or Swift: Objective-C
• iOS version: iPadOS 13.5.1
• Firebase SDK version: 6.14
• FirebaseUI version: 8.4.2
• CocoaPods Version: ____

Step 3: Describe the problem:

When doing an Apple Sign-In from an iPad the identityToken returned by Apple can sometime be null without invoking didCompleteWithError.
This cause an exception to be raised by FirebaseAuth as the idToken is null.

I have not been able to find yet what cause the identityToken to be null in the first place but I believe that the raised exception from FirebaseAuth should not crash the application and instead provide an error message in FirebaseUI.

[ttermeer-reboundcg]

After further investigation, I believe the issue is from this line in FUIOAuth.m
NSString *idToken = [NSString stringWithUTF8String:[appleIDCredential.identityToken bytes]];

My knowledge on Objective-C is limited but I read that if the data is not NUL terminated, it will not be able to convert it with this method.

[yuchenshi]

I've filed b/160628284 internally for further investigation.

[morganchen12]

Fixed in #881.