COVIDSafe code from version 2.0 (#37)

CovidSafe/RegistrationIntroViewController.swift

@@ -0,0 +1,45 @@
+//
+//  RegistrationIntroViewController.swift
+//  CovidSafe
+//
+//  Copyright © 2020 Australian Government. All rights reserved.
+//
+
+import UIKit
+import SafariServices
+import KeychainSwift
+
+class RegistrationIntroViewController: UIViewController {
+    
+    let keychain = KeychainSwift()
+    
+    override func viewWillAppear(_ animated: Bool) {
+        super.viewWillAppear(animated)
+        
+        switch UIApplication.shared.isProtectedDataAvailable {
+        case true  :
+            checkToken()
+            break
+        case false:
+            NotificationCenter.default.addObserver(self, selector: #selector(setKeychainAvailable(_:)), name: UIApplication.protectedDataDidBecomeAvailableNotification, object: nil)
+            break
+        }
+    }
+    
+    @objc
+    func setKeychainAvailable(_ notification: Notification) {
+        NotificationCenter.default.removeObserver(self, name: UIApplication.protectedDataDidBecomeAvailableNotification, object: nil)
+        checkToken()
+    }
+    
+    func checkToken() {
+        let isLoggedIn: Bool = (keychain.get("JWT_TOKEN") != nil)
+        
+        if isLoggedIn {
+            DispatchQueue.main.async {
+                let homeVC = HomeViewController(nibName: "HomeView", bundle: nil)
+                self.navigationController?.setViewControllers([homeVC], animated: true)
+            }
+        }
+    }
+}