I'm trying to install the ["drop-in" authentication solution](https://github.com/firebase/FirebaseUI-iOS) from [Firebase](https://firebase.google.com/docs/auth/) that automatically sends your app users through Google, Facebook, or email/password screens to authenticate them.

My problem is that the code provided by Firebase appears to be in the old iOS language of Objective C instead of Swift, and that some of the lines of instructional Swift code appear outdated, and I can't find the new lines I'm supposed to use.

I'm building my code mostly from the instructions on this part of the Github drop-in solution: [FirebaseUI Authentication](https://github.com/firebase/FirebaseUI-iOS/tree/master/FirebaseUI/Auth).

This has resulted in the following code, some of which I've had to guess at, since Xcode couldn't recognize `.authUI()` in `let authUI = FIRAuthUI.authUI()`. The app doesn't crash, but it's not starting the authentication process at all, either. It's just a blank screen.

```
import UIKit
import Firebase
import FirebaseAuth
import FirebaseDatabaseUI
import FirebaseAuthUI
import FirebaseGoogleAuthUI
import FirebaseFacebookAuthUI
import FBSDKCoreKit
import FBSDKLoginKit

class LoginController: UIViewController, FIRAuthUIDelegate {

var db = FIRDatabaseReference.init()
var kFacebookAppID = "15839856152xxxxx"
var kGoogleClientID = "9042861xxxxx-6qq4gmeos07gpgmgt54ospv3fvpg0724.apps.googleusercontent.com"

override func viewDidLoad() {
    super.viewDidLoad()

    //FIRApp.configure()
    let authUI = FIRAuthUI.defaultAuthUI()

    let facebookAuthUI = FIRFacebookAuthUI(appID: kFacebookAppID)
    let googleAuthUI = FIRGoogleAuthUI(clientID: kGoogleClientID)
    //let emailAuthUI = FIREmailPasswordAuthProvider

    authUI?.providers = [facebookAuthUI, googleAuthUI]

    // Present the auth view controller and then implement the sign in callback.
    let authViewController = authUI
    authUI?.authViewController()

}

func authUI(authUI: FIRAuthUI, didSignInWithUser user: FIRUser?, error: NSError?) {
    if error != nil {
        //Problem signing in
    }else {
        //User is in!
    }
}

func application(app: UIApplication, openURL url: NSURL, options: [String: AnyObject]) -> Bool {
    let sourceApplication = options[UIApplicationOpenURLOptionsSourceApplicationKey] as! String
    return FIRAuthUI.defaultAuthUI()!.handleOpenURL(url, sourceApplication: sourceApplication ?? "") ?? false
}

}

```

As a side not, I placed `FIRApp.configure()` inside the "didFinishLaunchingWithOptions" function in the AppDelegate class, and I have also separated `FIRApp.configure()` out as an override in the AppDelegate class, as shown below. Nothing seems to help. I've spent about 4 days trying to figure this out. Implementing it for Web and Android only took a few hours.

```
override init() {
    super.init()
    FIRApp.configure()
    //FIRDatabase.database().persistenceEnabled = true
}

```