I've sent an app invitation from an iPad app to a test Facebook account via Facebook's API. When I login to the test account on my PC, the app request is there.
When I login to the test account on my iPad (either via Safari or via the Facebook App), I can see the number "1" next to the App Centre tab, but when I click it and go to the App Centre, there's no request. In fact, I can't see any App Centre areas dedicated to requests on Facebook for iOS - there's only Social Picks and Top Apps. Any explanation for this?
This is caused by an incorrect configuration on the Facebook app setting page. When you are setting up the app, you need to make sure the following is set correctly.
developers.facebook.com then select "Apps". Edit your app and fill in the following..
iOS App Bundle (dont think it's essential but fill it in, this the bundle id from Xcode (com.companyname.appname))
iPhone/iPad App Store ID - This is ESSENTIAL, one of these must be filled in with a valid app store ID. You get this when you create an app with iTunes Connect. If you create an app, and fill in the details right up to the point where it asks you to submit the binary, it will generate what Apple refers to as an Apple ID (or iTunes Id?). It's just a long integer value. It doesn't have to be for the corresponding app, if you already have apps in the app store just log in to iTunes connect and use an existing one for testing.
Configured for iOS SSO - Enabled
Configured for Deep Linking - Enabled
The only functionality you get from Facebook when a user clicks an app notification on iOS is the user being redirected to the app, if installed, or to the App Store if not. Also if you want your app notifications to show up on desktop, you'll need a Canvas URL under the "App On Facebook" section.
In my tests I had to have a canvas URL to get iOS notifications working, but I'm not sure if this is a bug with Facebook or intended behaviour, so if it doesn't work with just iOS enabled, enable app on Facebook too and stick in a random url if you don't have one.