import UIKit
import AWSMobileClient

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        initializeAWSMobileClient() // Initialize the AWSMobileClient
    }
    
    // Use the iOS SDK drop-in Auth UI to show login options to user (Basic auth, Google, or Facebook)
    // Note: The view controller implementing the drpo-in auth UI needs to be associated with a Navigation Controller.
    func showSignIn() {
        AWSMobileClient.sharedInstance().showSignIn(navigationController: self.navigationController!, {
            (userState, error) in
            if(error == nil){   // Successful signin
                DispatchQueue.main.async {
                    print("User successfully logged in")
                }
            }
        })
    }
  //...
}