Share Facebook User ID between more than one application

Question

I have three application, every one use a Facebook application. I get the Facebook userInfo with Api as follows:

[[[FBRequest alloc] initWithSession:appDelegate.fbSession graphPath:@"me"] startWithCompletionHandler:
         ^(FBRequestConnection *connection,
           NSDictionary<FBGraphUser> *fbuser,
           NSError *error) {
             if (!error) {
                 NSLog(@"userid:%@",fbuser.id);
             }
         }];

If I use different Facebook application, fbuser.id is different. How could I make three application use the same fbuser.id?

Thanks.

Answer 1

With the introduction of Graph API v2.0, user_ids are app-scoped, meaning that the same user will have different user_ids with different apps.

See https://developers.facebook.com/docs/apps/upgrading#upgrading_v2_0_user_ids

There's the possibility to map the user_ids via the Business Mapping API:

https://developers.facebook.com/docs/apps/for-business

The Business Mapping API is only useful for businesses who operate multiple user-facing apps and whom need to map the same app-scoped user IDs across them, for cross-promotion for example.