How to place a VC in a navigation controller programmatically? - swift

Question

I am currently getting an error whenever I try to present this VC. The error is Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value I believe it is because the VC is not in a navigation controller. How do I put this VC in a navigation controller(programmatically).
import UIKit
import AWSAuthCore
import AWSAuthUI
import AWSMobileClient
class SignInViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
AWSMobileClient.default()
.showSignIn(navigationController: self.navigationController!, // this is where i get the error.
signInUIOptions: SignInUIOptions(
canCancel: true,
logoImage: UIImage(named: "MyCustomLogo"),
backgroundColor: UIColor.red)) { (result, err) in
AWSMobileClient.default().initialize { (userState, error) in
if let userState = userState {
switch(userState){
case .signedIn:
DispatchQueue.main.async {
}
case .signedOut:
AWSMobileClient.default().showSignIn(navigationController: self.navigationController!, { (userState, error) in
if(error == nil){ //Successful signin
DispatchQueue.main.async {
}
}
})
default:
AWSMobileClient.default().signOut()
}
} else if let error = error {
print(error.localizedDescription)
}
}
}
}
}
Here is the code from AppDelegate
import UIKit
import AWSAppSync
import AWSMobileClient
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
var appSyncClient: AWSAppSyncClient?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
let nav1 = UINavigationController()
let mainView = SignInViewController(nibName: nil, bundle: nil)
nav1.viewControllers = [mainView]
self.window!.rootViewController = nav1
// Override point for customization after application launch.
window = UIWindow(frame: UIScreen.main.bounds)
window?.rootViewController = UINavigationController(rootViewController: TabBarController())
window?.makeKeyAndVisible()
AWSMobileClient.default().addUserStateListener(self) { (userState, info) in
switch (userState) {
case .guest:
print("user is in guest mode.")
case .signedOut:
self.window?.rootViewController?.present(SignInViewController(), animated: true, completion: nil)
print("user signed out.")
case .signedIn:
print("user is signed in.")
case .signedOutUserPoolsTokenInvalid:
print("need to login again.")
case .signedOutFederatedTokensInvalid:
print("user logged in via federation, but currently needs new tokens")
default:
print("unsupported")
}
}
AWSMobileClient.default().initialize { (userState, error) in
if let userState = userState {
print("UserState: \(userState.rawValue)")
} else if let error = error {
print("error: \(error.localizedDescription)")
}
}
do {
// You can choose the directory in which AppSync stores its persistent cache databases
let cacheConfiguration = try AWSAppSyncCacheConfiguration()
// AppSync configuration & client initialization
let appSyncServiceConfig = try AWSAppSyncServiceConfig()
let appSyncConfig = try AWSAppSyncClientConfiguration(appSyncServiceConfig: appSyncServiceConfig,
cacheConfiguration: cacheConfiguration)
appSyncClient = try AWSAppSyncClient(appSyncConfig: appSyncConfig)
print("Initialized appsync client.")
} catch {
print("Error initializing appsync client. \(error)")
}
return true
}
// MARK: UISceneSession Lifecycle
func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
// Called when a new scene session is being created.
// Use this method to select a configuration to create the new scene with.
return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
}
func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
// Called when the user discards a scene session.
// If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
// Use this method to release any resources that were specific to the discarded scenes, as they will not return.
}
}

Answer 1

Embed the SignInViewController in a UINavigationController.
To do that, drag-and-drop a UINavigationController to the Storyboard and CTRL + drag from that UINavigationController to the SignInViewController, choose the relationship rootViewController
Programatically:
var nav1 = UINavigationController()
var mainView = SignInViewController(nibName: nil, bundle: nil)
nav1.viewControllers = [mainView]
self.window!.rootViewController = nav1