Swift 3 / Xcode 8.2 - switch view in viewDidLoad not working

Question

I want to switch the ViewController on load when the user is already logged in. The problem: The view didnt change when user is equal to "true"...

Thank you in advance!!

override func viewDidLoad() {
    super.viewDidLoad()

    var user: String?
    user = UserDefaults.standard.value(forKey: "loginSuccessfull") as? String

    if user == "true" {
        let vc = self.storyboard?.instantiateViewController(withIdentifier: "SecondView") as UIViewController!
        self.show(vc!, sender: vc)
    }

    // Do any additional setup after loading the view, typically from a nib.
}

Answer 1

Remove the code from viewDidLoad method and use the below method.

 override func viewDidAppear() {
     guard let user = UserDefaults.standard.string(forKey: "loginSuccessfull"), user == "true" else {
      return
     }
     let vc = self.storyboard?.instantiateViewController(withIdentifier: "SecondView")!
     self.present(vc, animated: true)
 }

Answer 2

You should put the code in which you display the second View Controller in either viewWillAppear() or viewDidAppear().

override func viewDidAppear() {
    super.viewDidAppear()

    var user: String?
    user = UserDefaults.standard.value(forKey: "loginSuccessfull") as? String

    if user == "true" {
        let vc = self.storyboard?.instantiateViewController(withIdentifier: "SecondView") as UIViewController!
        self.show(vc!, sender: vc)
    }

    // Do any additional setup after loading the view, typically from a nib.
}

Reason being that during viewDidLoad() some of the properties of your ViewController has not been defined and it is not ready to present another ViewController.