facebook ios url types issue - ios

Question

I'm a beginner in the iOS (native) world, I have a strange issue with the Facebook authentication in my demo app.
I've configured the .plist file with the following keys following the tutorial:
FacebbokAppID: <myappid>
FacebookDisplayName: a name
Url types (array)
Item 0 (dictionary)
Url Schemes (Array)
Item 0 (String): fb<myappid>
Where <myappid> is the numerical app id of the registered app on the facebook website.
Now, I perform the login using this code:
- (void) facebookLoginLogout
{
// If the session state is any of the two "open" states when the button is clicked
if (FBSession.activeSession.state == FBSessionStateOpen
|| FBSession.activeSession.state == FBSessionStateOpenTokenExtended) {
// Close the session and remove the access token from the cache
// The session state handler (in the app delegate) will be called automatically
[FBSession.activeSession closeAndClearTokenInformation];
// If the session state is not any of the two "open" states when the button is clicked
} else {
// Open a session showing the user the login UI
// You must ALWAYS ask for basic_info permissions when opening a session
[FBSession openActiveSessionWithReadPermissions:#[#"basic_info", #"friends_online_presence"]
allowLoginUI:YES
completionHandler:
^(FBSession *session, FBSessionState state, NSError *error) {
// Retrieve the app delegate
AppDelegate* appDelegate = [UIApplication sharedApplication].delegate;
// Call the app delegate's sessionStateChanged:state:error method to handle session state changes
[appDelegate sessionStateChanged:session state:state error:error];
}];
}
}
And I've defined the method to handle state changes:
- (void)sessionStateChanged:(FBSession *)session state:(FBSessionState) state error:(NSError *)error
{
NSLog(#"here?");
[..]
}
The problem is exactly that this method is never called in this situation.
THE STRANGE POINT is that, if I change Url types -> Item 0 -> Url Schemes -> Item 0 value to something different, the method is called!
Any hints? Thanks in advance.