Back button disappears after creating AppDelegate in Swift 3.0 - ios

Question

I created the structure as below in xcode 8 swift 3.0.
Before I add AppDelegate code. Back button still appear fine on Apply, Apply Behalf and Profile controller.
I use segue to open page.
But after I add AppDelegate code into Homepage and Login controllers , back button disappears on Apply, Apply behalf and profile controller page.
Can someone help or explain why is this happening ? How to enable back the back button on apply, apply behalf and profile page ?
Thanks.
Home.swift
import UIKit
class ViewController: UIViewController {
#IBOutlet var staffNumberLbl: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
staffNumberLbl.text = UserDefaults.standard.object(forKey: "login") as? String
}
override func viewDidAppear(_ animated: Bool) {
let isUserLoggedIn = UserDefaults.standard.bool(forKey: "loggedIn")
if(!isUserLoggedIn){
self.performSegue(withIdentifier: "loginview", sender: self)
}
}
#IBAction func logoutData(_ sender: Any) {
UserDefaults.standard.set(false, forKey: "loggedIn")
UserDefaults.standard.synchronize();
let loginViewController = self.storyboard!.instantiateViewController(withIdentifier: "loginview") as! LoginViewController
let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.window?.rootViewController = loginViewController
appDelegate.window?.makeKeyAndVisible()
}
}
Login.swift
import UIKit
class LoginViewController: UIViewController {
#IBOutlet var loginlbl: UITextField!
#IBOutlet var passlbl: UITextField!
#IBOutlet var login_button: UIButton!
var login: String!
var pw: String!
override func viewDidLoad() {
super.viewDidLoad()
}
#IBAction func loginData(_ sender: Any) {
login = loginLbl.text
pw = passLbl.text
if(login == "" || pw == ""){
return
}
else{
let url = URL(string: "http://localhost/login.php")
let session = URLSession.shared
let request = NSMutableURLRequest(url: url! as URL)
request.httpMethod = "POST"
let LoginDataToPost = "login=\(login!)&pw=\(pw!)"
request.httpBody = LoginDataToPost.data(using: String.Encoding.utf8)
let task = session.dataTask(with: request as URLRequest, completionHandler: {
(data, response, error) in
if error != nil {
return
}
else {
do {
if let json = try JSONSerialization.jsonObject(with: data!) as? [String: String]
{
DispatchQueue.main.async
{
let message = Int(json["message"]!)
let login = json["login"]
if(message == 1) {
UserDefaults.standard.set(true, forKey: "isUserLoggedIn")
UserDefaults.standard.set(login, forKey: "login")
UserDefaults.standard.synchronize();
self.dismiss(animated: true, completion: nil)
let myViewController:ViewController = self.storyboard!.instantiateViewController(withIdentifier: "ViewController") as! ViewController
let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.window?.rootViewController = myViewController
appDelegate.window?.makeKeyAndVisible()
print("Value for login is : \(login!)")
return
}
else {}
}
}
else {}
}
catch let jsonParse {}
}
})
task.resume()
}
}
}
AppDelegate.swift
import UIKit
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
let mainStoryBoard: UIStoryboard = UIStoryboard(name: "Main", bundle:nil)
let isUserLoggedIn:Bool = UserDefaults.standard.bool(forKey: "isUserLoggedIn")
if(!isUserLoggedIn) {
let loginViewController = mainStoryBoard.instantiateViewController(withIdentifier: "loginview") as! LoginViewController
window!.rootViewController = loginViewController
window!.makeKeyAndVisible()
}
else {
let homePage = mainStoryBoard.instantiateViewController(withIdentifier: "ViewController") as! ViewController
window!.rootViewController = homePage
window!.makeKeyAndVisible()
}
return true
}
}

Answer 1

You are setting rootviewcontroller without embedding navigation controller to it in logoutData & loginData function.
Use this code :
let navigationController = UINavigationController.init(rootViewController: myViewController)
appDelegate.window?.rootViewController = navigationController
Use this code in AppDelegate:
if(!isUserLoggedIn) {
let loginViewController = mainStoryBoard.instantiateViewController(withIdentifier: "loginview") as! LoginViewController
let navigationController = UINavigationController.init(rootViewController: loginViewController)
appDelegate.window?.rootViewController = navigationController
window!.makeKeyAndVisible()
}
else {
let homePage = mainStoryBoard.instantiateViewController(withIdentifier: "ViewController") as! ViewController
let navigationController = UINavigationController.init(rootViewController: homePage)
appDelegate.window?.rootViewController = navigationController
window!.makeKeyAndVisible()
}

Answer 2

Remove this from Home.swift,
let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.window?.rootViewController = loginViewController
appDelegate.window?.makeKeyAndVisible()
because its not inheriting the properties of Navigation controller
and add it in Appdelegate.swift file
For the other 3 viewcontrollers, you need to add the Navigation controller between eachSegway in order to inherit it or code the button by instantiating the viewcontrollers respectively

Answer 3

After successful login,try to make NavigationController as rootViewController instead of your ViewController
Your back button will start appearing.
In AppDelegate, in else block, instead of this line
let homePage = mainStoryBoard.instantiateViewController(withIdentifier: "ViewController") as! ViewController
write this
let homePage = mainStoryBoard.instantiateViewController(withIdentifier: "NavigationController") as! UINavigationController
Inside LoginViewController, in the block if(message == 1)
replace
let myViewController:ViewController = self.storyboard!.instantiateViewController(withIdentifier: "ViewController") as! ViewController
with
let navController:UINavigationController = self.storyboard!.instantiateViewController(withIdentifier: "NavigationController") as! UINavigationController
Also set storyboard identifier for UINavigationController in storyboard to NavigationController

Answer 4

Depending on your configuration:
self.navigationItem.hidesBackButton = YES;
OR:
self.navigationController.navigationItem.hidesBackButton = YES;
Or, if you just want to disable the button without hiding it, you can use this.
self.navigationController.navigationItem.backBarButtonItem.enabled = NO;