Authenticate user in Share Extension with Firebase

问题

I've been struggling with his for quite some time now.. I have an app and also a Share Extension.

Inside the Share Extension the user needs to be authenticated so he can make requests to my Cloud-Firestore (I set up the security rules so only authorized user can access data). However I am not able to authenticate the user inside my Share Extension.

I already checked out Firebase Documentation and this SO-Question but that didn't help me.

In my case the user can sign in with Email, Google, Facebook & Apple.

I tried calling this inside App-Delegate didFinishLaunchingWithOptions and in my ShareExtension inside viewDidLoad right after I call Firebase.configure():

    do {
        try Auth.auth().useUserAccessGroup(UserDefaults.Keys.accessGroupKey)
    } catch let error as NSError {
      print("Error changing user access group: %@", error)
    }

But when trying to call Auth.auth.currentUser! inside my ShareExtension it always fails with a nil-error.

Update: When calling the code above on a clean simulator device it fails with this error:

Error changing user access group: %@ Error Domain=FIRAuthErrorDomain Code=17995 "An error occurred when accessing the keychain. The @c NSLocalizedFailureReasonErrorKey field in the @c NSError.userInfo dictionary will contain more information about the error encountered" UserInfo={FIRAuthErrorUserInfoNameKey=ERROR_KEYCHAIN_ERROR, NSLocalizedFailureReason=SecItemCopyMatching (-34018), NSLocalizedDescription=An error occurred when accessing the keychain. The @c NSLocalizedFailureReasonErrorKey field in the @c NSError.userInfo dictionary will contain more information about the error encountered}

In Signing & Capabilities I have enabled App-Groups for both app and extension with the same identifier. Same goes for Keychain-Sharing. The identifier I am using there is the same as UserDefautls.Keys.accessGroupKey from the code above.

I am really struggling with this topic and I couldnt find a Step-by-step guide that is working for me. I feel like I am missing something, only calling the code above is not doing anything for me. If anyone can help me out here I am more then grateful!

If anything is unclear or you need more info just let me know!

来源：https://stackoverflow.com/questions/64668523/authenticate-user-in-share-extension-with-firebase