FBSession.openActiveSessionWithReadPermissions not calling completionHandler - ios

Question

I'm implementing OAuth login using Facebook SDK, but the FBSession.openActiveSessionWithReadPermissions:allowLoginUI:completionHandler method is not calling the completionHandler nor is it returning "true", which would indicate a cached token. Everything else seems to work fine, except this. What's wrong with this code?
var completionHandler: FBSessionStateHandler = {
session, status, error in
NSLog("token not cached");
if error {
// Login failed for some reason, so we notify the delegate.
self.delegate.didFailOpenningSession?(self, withError: ErrorUtility.error(
code: .FailedOpenningSession,
withFacebookError: error
));
// Don't proceed on errors
return;
}
// Session is now open, we should notify the delegate
self.delegate.didOpenSession?(self);
};
NSLog("here");
// Open the session, prompting the user if necessary. This might send the application to the background
if FBSession.openActiveSessionWithReadPermissions(["public_profile"], allowLoginUI: true, completionHandler: completionHandler) {
NSLog("Token cached");
// If we end up here, the session token must exist, so we now have an open session
self.delegate.didOpenSession?(self);
}
Edit: I forgot to mention that the NSLog logs "here", but not "Token cached" nor "token not cached"
Edit: Now things got a bit stranger. When my app launches I show a screen with a Facebook login button. When the user presses the button the code above gets triggered. After I authorise the app, the app gets back to the same screen (it shouldn't, but I can't do it any other way until the completion handler gets called). Then I tried pressing the button again and now I do get the logs.
This is what I get:
here
token not cached
here
The first line is from the first button press, the other two appear when I press it the second time. Now what's so odd about it? Shouldn't "token not cached" and "here" be reversed??? Is it calling the competionHandler from the last call or something?
Nevermind, that much is fixed.
Edit: one other thing. If I press the button multiple times, I always get "token not cached". I think it should be caching

Answer 1

It's solved. I was missing the method AppDelegate.application:handleOpenURL -> Bool

Answer 2

First ensure that you are using correct closure syntax. You are not providing a matching closure callback for the block callback.
notice the block callback for the FB session is:
^(FBSession *session,
FBSessionState state, NSError *error)
You should have
/*function parameters*/){ session, state, error in
//closure declaration goes at the top after the {
//Insert logic here
NSLog("Token cached");
}
This will equate to
FBSession.openActiveSessionWithReadPermissions(permissions, allowLoginUI:true){ session, state, error in
//callback code body here
}

Answer 3

This usually because of missing handle seesion in app’s application:openURL function.
It is in AppDelegate.m. Description from facebook samples says below:
// During the Facebook login flow, your app passes control to the Facebook iOS app or Facebook in a mobile browser.
// After authentication, your app will be called back with the session information.
// Override application:openURL:sourceApplication:annotation to call the FBsession object that handles the incoming URL
- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication
annotation:(id)annotation
{
return [FBSession.activeSession handleOpenURL:url];
}