This library is similar to the B4A GoogleIdentity library: https://www.b4x.com/android/forum/threads/googleidentity-sign-in-with-google.66432/#content
It requires some configuration:
1. Follow the steps listed in step #2: https://developers.google.com/identity/toolkit/ios/quickstart#step_1_get_the_quick-start_app
You need to have two keys at the end:
a. API key (Type = iOS)
b. OAuth 2.0 Client Id (Type = iOS)
2. Add the following attributes:
#UrlScheme: <your package name> #UrlScheme: com.googleusercontent.apps.<first part of the the client id>
3. Initialize the IdentityClient:
git.Initialize("git", <API key>, <client id>)
4. Call IdentityClient.SigninWithGoogle
5. Handle the Signin event.
The library XML file is attached.
If you are using a local Mac builder then you can download the required files from: www.b4x.com/b4i/files/GoogleIdentity.zip
An example project is attached. You will need to change the ids.