add: last used category

Billing.Shared/Models/Category.cs

@@ -1,5 +1,6 @@
 using SQLite;
-
+using System;
+
 namespace Billing.Models
 {
     public class Category : IIdItem
@@ -14,6 +15,8 @@ namespace Billing.Models
         public string Name { get; set; }
         public long TintColor { get; set; } = TRANSPARENT_COLOR;
         public int? ParentId { get; set; }
+        public DateTime? LastUsed { get; set; }
+        public int? LastAccountId { get; set; }
     }
 
     public enum CategoryType

Billing.Shared/Views/AddBillPage.xaml.cs

@@ -170,6 +170,9 @@ namespace Billing.Views
                     Store = Store,
                     Note = Note
                 });
+
+                category.LastAccountId = walletId;
+                category.LastUsed = DateTime.Now;
             }
         }
 
@@ -190,6 +193,14 @@ namespace Billing.Views
         private void CategorySelectPage_Tapped(object sender, UICategory e)
         {
             categoryId = e.Category.Id;
+            if (e.Category.LastAccountId != null)
+            {
+                var wallet = App.Accounts.FirstOrDefault(a => a.Id == e.Category.LastAccountId.Value);
+                if (wallet != null)
+                {
+                    SetValue(WalletNameProperty, wallet.Name);
+                }
+            }
             SetValue(CategoryNameProperty, e.Name);
         }