Facebook SDK login never calls back my application on iOS 9

Turns out that on iOS 9 when UIApplicationDelegate‘s application:openURL:options: is implemented, application:openURL:sourceApplication:annotation: will not get called.

So what I had to do is call FBSDKApplicationDelegate‘s application:openURL:sourceApplication:annotation: from UIApplicationDelegate‘s application:openURL:options:

- (BOOL)application:(UIApplication *)app openURL:(NSURL *)url options:(NSDictionary<NSString*, id> *)options {
    return [[FBSDKApplicationDelegate sharedInstance] application:app
                                                      openURL:url
                                            sourceApplication:options[UIApplicationOpenURLOptionsSourceApplicationKey]
                                                   annotation:options[UIApplicationOpenURLOptionsAnnotationKey]];
}