Fix Facebook Login in Swift sample app.

Author: rosalyntan

samples/swift/FirebaseUI-demo-swift/FUIAppDelegate.swift

@@ -15,6 +15,7 @@
 //
 
 import UIKit
+import FBSDKCoreKit
 import Firebase
 import FirebaseAuthUI
 import GTMSessionFetcher
@@ -29,11 +30,21 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
     // accompanying valid GoogleService-Info.plist file.
     FirebaseApp.configure()
     GTMSessionFetcher.setLoggingEnabled(true)
+    ApplicationDelegate.shared.application(
+        application,
+        didFinishLaunchingWithOptions: launchOptions
+    )
     return true
   }
 
   @available(iOS 9.0, *)
   func application(_ app: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey : Any]) -> Bool {
+    ApplicationDelegate.shared.application(
+        app,
+        open: url,
+        sourceApplication: options[UIApplication.OpenURLOptionsKey.sourceApplication] as? String,
+        annotation: options[UIApplication.OpenURLOptionsKey.annotation]
+    )
     let sourceApplication = options[UIApplication.OpenURLOptionsKey.sourceApplication] as! String?
     return self.handleOpenUrl(url, sourceApplication: sourceApplication)
   }