show（）视图控制器不起作用

Question

I try to authenticate the user of my app if they are not. I first read the value saved in UserDefaults to know if they are logged in, and if not, I want to show the ViewController to allow them to log in.

But anyway, the LogInViewController won't show, this is my code :

import UIKit
import MapKit

class MainViewController: UIViewController, CLLocationManagerDelegate {

override func viewDidLoad() {
    super.viewDidLoad()

    if(!UserDefaults.standard.bool(forKey: "userIsConnected")){
         let LogVC = self.storyboard?.instantiateViewController(withIdentifier: "LogInViewController") as! LogInViewController
         show(LogVC, sender: self)
    }
}

I also tried without the 'if' condition, and it doesn't work anymore

EDIT : I also tried presentVC() and I had the error "Attempt to present on whose view is not in the window hierarchy"

Thanks for help

Answer 1

You are trying to login in the MainViewController . You should avoid when possible managing your login in a view controller. The login is more effective if managed in your AppDelegate .

Add this code to didFinishLaunchingWithOptions in AppDelegate.swift

if !UserDefaults.standard.bool(forKey: "userIsConnected") {
      let storyboard = UIStoryboard(name: "Main", bundle: Bundle.main)
      let loginViewController = storyboard.instantiateViewController(withIdentifier: "LogInViewController")
      window?.makeKeyAndVisible()
      window?.rootViewController?.present(loginViewController, animated: true, completion: nil
}

Make sure you can access UserDefaults .