Google 400 Error: invalid request Custom scheme URIs are not allowed for 'Web' client type
My guess is that your client is registered incorrectly in Google Cloud Console. A 'WEB' client is typically a server or Javascript application. An iOS app should be registered as an iOS client.
https://developers.google.com/identity/protocols/OAuth2InstalledApp#creatingcred
I Just found this problem too.
Please check google developer console and look at the credentials keys
Your Client ID in google-info plist must come from iOS application, not the web.
And use that Client ID to be revereseClientID and copy it in to URI type
I have solved the problems by create project in Fire Base Because REVERSED_CLIENT_ID generate from developers.google.com Incorrect.Try create your project in FireBasehttps://console.firebase.google.com