Add logout button to preferences

Tusker/AppDelegate.swift

@@ -22,6 +22,8 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
             showOnboardingUI()
         }
         
+        NotificationCenter.default.addObserver(self, selector: #selector(onUserLoggedOut), name: .userLoggedOut, object: nil)
+        
         window!.makeKeyAndVisible()
         
         return true
@@ -94,6 +96,10 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
         window!.rootViewController = onboarding
     }
     
+    @objc func onUserLoggedOut() {
+        showOnboardingUI()
+    }
+
 }
 
 extension AppDelegate: OnboardingViewControllerDelegate {

Tusker/LocalData.swift

@@ -68,3 +68,7 @@ class LocalData {
     }
     
 }
+
+extension Notification.Name {
+    static let userLoggedOut = Notification.Name("userLoggedOut")
+}

Tusker/Screens/Preferences/PreferencesView.swift

@@ -8,10 +8,23 @@
 import SwiftUI
 
 struct PreferencesView : View {
+    @State private var showingLogoutConfirmation = false
+    
     var body: some View {
         // workaround: the navigation view is provided by MyProfileTableViewController so that it can inject the Done button
 //        NavigationView {
             List {
+                Section {
+                    Button(action: {
+                        self.showingLogoutConfirmation = true
+                    }) {
+                        Text("Logout")
+                    }.alert(isPresented: $showingLogoutConfirmation) {
+                        Alert(title: Text("Are you sure you want to logout?"), message: nil, primaryButton: .destructive(Text("Logout"), action: self.logoutPressed), secondaryButton: .cancel())
+                    }
+                }
+                
+                Section {
                     NavigationLink(destination: AppearancePrefsView()) {
                         Text("Appearance")
                     }
@@ -25,6 +38,7 @@ struct PreferencesView : View {
                         Text("Advanced")
                     }
                 }
+            }
                 .listStyle(GroupedListStyle())
                 .navigationBarTitle(Text("Preferences"), displayMode: .inline)
                 .onDisappear {
@@ -33,6 +47,15 @@ struct PreferencesView : View {
                 }
 //        }
     }
+    
+    func logoutPressed() {
+        LocalData.shared.onboardingComplete = false
+        LocalData.shared.instanceURL = nil
+        LocalData.shared.clientID = nil
+        LocalData.shared.clientSecret = nil
+        LocalData.shared.accessToken = nil
+        NotificationCenter.default.post(name: .userLoggedOut, object: nil)
+    }
 }
 
 #if DEBUG