Replaced async void methods with async Task.

Author: David Britch

src/Mobile/eShopOnContainers/eShopOnContainers.Core/ViewModels/BasketViewModel.cs

@@ -59,7 +59,7 @@ public decimal Total
             }
         }
 
-        public ICommand AddCommand => new Command<BasketItem>(AddItem);
+        public ICommand AddCommand => new Command<BasketItem>(async (item) => await AddItemAsync(item));
 
         public ICommand CheckoutCommand => new Command(async () => await CheckoutAsync());
 
@@ -80,22 +80,22 @@ public override async Task InitializeAsync(object navigationData)
                 foreach (var basketItem in basket.Items)
                 {
                     BadgeCount += basketItem.Quantity;
-                    AddBasketItem(basketItem);
+                    await AddBasketItemAsync(basketItem);
                 }
             }
 
             MessagingCenter.Unsubscribe<CatalogViewModel, CatalogItem>(this, MessengerKeys.AddProduct);
-            MessagingCenter.Subscribe<CatalogViewModel, CatalogItem>(this, MessengerKeys.AddProduct, (sender, arg) =>
+            MessagingCenter.Subscribe<CatalogViewModel, CatalogItem>(this, MessengerKeys.AddProduct, async (sender, arg) =>
             {
                 BadgeCount++;
 
-                AddCatalogItem(arg);
+                await AddCatalogItemAsync(arg);
             });
 
             await base.InitializeAsync(navigationData);
         }
 
-        private void AddCatalogItem(CatalogItem item)
+        private async Task AddCatalogItemAsync(CatalogItem item)
         {
             BasketItems.Add(new BasketItem
             {
@@ -106,26 +106,26 @@ private void AddCatalogItem(CatalogItem item)
                 Quantity = 1
             });
 
-            ReCalculateTotal();
+            await ReCalculateTotalAsync();
         }
 
-        private void AddItem(BasketItem item)
+        private async Task AddItemAsync(BasketItem item)
         {
             BadgeCount++;
 
-            AddBasketItem(item);
+            await AddBasketItemAsync(item);
 
             RaisePropertyChanged(() => BasketItems);
         }
 
-        private void AddBasketItem(BasketItem item)
+        private async Task AddBasketItemAsync(BasketItem item)
         {
             BasketItems.Add(item);
 
-            ReCalculateTotal();
+            await ReCalculateTotalAsync();
         }
 
-        private async void ReCalculateTotal()
+        private async Task ReCalculateTotalAsync()
         {
             Total = 0;
 

src/Mobile/eShopOnContainers/eShopOnContainers.Core/ViewModels/CatalogViewModel.cs

@@ -88,9 +88,9 @@ public CatalogType Type
 
         public ICommand AddCatalogItemCommand => new Command<CatalogItem>(AddCatalogItem);
 
-        public ICommand FilterCommand => new Command(Filter);
+        public ICommand FilterCommand => new Command(async () => await FilterAsync());
 
-        public ICommand ClearFilterCommand => new Command(ClearFilter);
+		public ICommand ClearFilterCommand => new Command(async () => await ClearFilterAsync());
 
         public override async Task InitializeAsync(object navigationData)
         {
@@ -110,7 +110,7 @@ private void AddCatalogItem(CatalogItem catalogItem)
             MessagingCenter.Send(this, MessengerKeys.AddProduct, catalogItem);
         }
 
-        private async void Filter()
+        private async Task FilterAsync()
         {
             if (Brand == null && Type == null)
             {
@@ -126,7 +126,7 @@ private async void Filter()
             IsBusy = false;
         }
 
-        private async void ClearFilter()
+        private async Task ClearFilterAsync()
         {
             IsBusy = true;
 

src/Mobile/eShopOnContainers/eShopOnContainers.Core/Views/CatalogView.xaml.cs

@@ -8,14 +8,12 @@ namespace eShopOnContainers.Core.Views
 {
     public partial class CatalogView : ContentPage, IMenuContainerPage
     {
-        private FiltersView _filterView;
+        private FiltersView _filterView = new FiltersView();
 
         public CatalogView()
         {
             InitializeComponent();
 
-            _filterView = new FiltersView();
-
             SlideMenu = _filterView;
 
             MessagingCenter.Subscribe<CatalogViewModel>(this, MessengerKeys.Filter, (sender) =>
@@ -42,13 +40,11 @@ public SlideMenuView SlideMenu
             set;
         }
 
-
         protected override void OnBindingContextChanged()
         {
             base.OnBindingContextChanged();
 
-			if (_filterView != null)
-	            _filterView.BindingContext = BindingContext;
+            _filterView.BindingContext = BindingContext;
         }
 
         private void OnFilterChanged(object sender, EventArgs e)