What to set the redirectUri for Apple SignIn with Flutter for android

Question

In my flutter app I'm attempting to setup apple sign in on android using the sign_in_with_apple_package I'm having trouble figuring out what to set the redirectUri to.

This is what I have:

appleCredential = await SignInWithApple.getAppleIDCredential(
   scopes: [
     AppleIDAuthorizationScopes.email,
     AppleIDAuthorizationScopes.fullName,
   ],
   webAuthenticationOptions: WebAuthenticationOptions(
     clientId: "SERVICE_IDENTIFIER",
     redirectUri: NEED_THIS,
   ),
 );

The package docs say to use: intent://callback?${PARAMETERS FROM CALLBACK BODY}#Intent;package=YOUR.PACKAGE.IDENTIFIER;scheme=signinwithapple;end with a pretty confusing description.

I'm using a django backend so the apple sign in going through that, everything is working on iOS, if I provide a redirectUrl like https://MY_DOMAIN/accounts/apple/login/callback the apple sign in flow works, but at the end goes to a page not found.

So maybe the real question is, what do I need that redirect url to do on the server? The sing_in_with_apple example has a comment for Android you will be using the API server that redirects back into your app via a deep link

So does this mean I need to deep link my redirect url back to my android app? Has anyone done this?

Answer 1

In WebAuthenticationOptions, redirectUri will change depending on your platform. On ios and web, you can just put your domain name. On android, you need to pass in a uri from your own server which will return a redirect to an android deep link.

Here's an example of the flutter code:

final credential = await SignInWithApple.getAppleIDCredential(
          scopes: [AppleIDAuthorizationScopes.email],
          webAuthenticationOptions: WebAuthenticationOptions(
              clientId: userService.platform != "apple"
                  ? 'com.example-service.example'
                  : 'com.example.example',
              redirectUri: userService.platform == "android" ?
            Uri.parse('https://example.com/apple/login/callback')
            : Uri.parse('https://example.com')));

Here's an example of the callback endpoint that should be added to your own server in python with fastapi:

@router.post("/apple/login/callback", response_class=RedirectResponse)
async def android_siwa(request: Request):
    args = ""
    form = await request.form()
    data = {k: v for k, v in form.items() if k != "upload-file"}
    for k, v in data.items():
        args += f"{k}={v}&"
    args = args[:-1]
    return f"intent://callback?{args}#Intent;package={settings.ANDROID_PACKAGE_NAME};scheme=signinwithapple;end"

And last thing, make sure to include both redirect URIs in your service id configuration: https://developer.apple.com/account/resources/identifiers/list/serviceId