added lock fingerprint page. added view for ios to hide app when backgrounded from multitask window.

src/App/App.cs

@@ -5,6 +5,10 @@ using System.Text;
 using Bit.App.Abstractions;
 using Bit.App.Pages;
 using Xamarin.Forms;
+using System.Diagnostics;
+using Plugin.Fingerprint.Abstractions;
+using System.Threading.Tasks;
+using Plugin.Settings.Abstractions;
 
 namespace Bit.App
 {
@@ -12,11 +16,19 @@ namespace Bit.App
     {
         private readonly IDatabaseService _databaseService;
         private readonly IAuthService _authService;
+        private readonly IFingerprint _fingerprint;
+        private readonly ISettings _settings;
 
-        public App(IAuthService authService, IDatabaseService databaseService)
+        public App(
+            IAuthService authService,
+            IDatabaseService databaseService,
+            IFingerprint fingerprint,
+            ISettings settings)
         {
             _databaseService = databaseService;
             _authService = authService;
+            _fingerprint = fingerprint;
+            _settings = settings;
 
             if(authService.IsAuthenticated)
             {
@@ -28,22 +40,40 @@ namespace Bit.App
             }
 
             MainPage.BackgroundColor = Color.FromHex("ecf0f5");
+
+            MessagingCenter.Subscribe<App>(this, "Lock", async (sender) =>
+            {
+                await CheckLockAsync();
+            });
         }
 
         protected override void OnStart()
         {
             // Handle when your app starts
+            CheckLockAsync();
             _databaseService.CreateTables();
+
+            Debug.WriteLine("OnStart");
         }
 
         protected override void OnSleep()
         {
             // Handle when your app sleeps
+            Debug.WriteLine("OnSleep");
         }
 
         protected override void OnResume()
         {
             // Handle when your app resumes
+            Debug.WriteLine("OnResume");
+        }
+
+        private async Task CheckLockAsync()
+        {
+            if(_authService.IsAuthenticated && Current.MainPage.Navigation.ModalStack.LastOrDefault() as LockFingerprintPage == null)
+            {
+                await Current.MainPage.Navigation.PushModalAsync(new LockFingerprintPage(), false);
+            }
         }
     }
 }