Bump to C# 10, minor code tweaks

Author: Sergio0694

samples/Directory.Build.props

@@ -0,0 +1,6 @@
+<Project>
+  <PropertyGroup>
+    <LangVersion>10.0</LangVersion>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+</Project>

samples/MvvmSample.Core/Docs/PuttingThingsTogether.md

@@ -178,7 +178,6 @@ public interface ISettingsService
     /// </summary>
     /// <typeparam name="T">The type of the object to retrieve.</typeparam>
     /// <param name="key">The key associated to the requested object.</param>
-    [Pure]
     T GetValue<T>(string key);
 }
 ```

samples/MvvmSample.Core/MvvmSample.Core.csproj

@@ -2,8 +2,6 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
-    <LangVersion>9.0</LangVersion>
-    <Nullable>enable</Nullable>
     <UserSecretsId>4e66f7b4-01a8-4f00-8733-4ae6a08c741f</UserSecretsId>
   </PropertyGroup>
 

samples/MvvmSample.Core/Services/ISettingsService.cs

@@ -3,7 +3,6 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
-using System.Diagnostics.Contracts;
 
 namespace MvvmSample.Core.Services
 {
@@ -18,14 +17,13 @@ public interface ISettingsService
         /// <typeparam name="T">The type of the object bound to the key.</typeparam>
         /// <param name="key">The key to check.</param>
         /// <param name="value">The value to assign to the setting key.</param>
-        void SetValue<T>(string key, T value);
+        void SetValue<T>(string key, T? value);
 
         /// <summary>
         /// Reads a value from the current <see cref="IServiceProvider"/> instance and returns its casting in the right type.
         /// </summary>
         /// <typeparam name="T">The type of the object to retrieve.</typeparam>
         /// <param name="key">The key associated to the requested object.</param>
-        [Pure]
         T? GetValue<T>(string key);
     }
 }

samples/MvvmSampleUwp/Converters/TaskResultConverter.cs

@@ -6,6 +6,8 @@
 using System.Threading.Tasks;
 using Windows.UI.Xaml.Data;
 
+#nullable enable
+
 namespace Microsoft.Toolkit.Uwp.UI.Converters
 {
     /// <summary>
@@ -15,7 +17,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Converters
     public sealed class TaskResultConverter2 : IValueConverter
     {
         /// <inheritdoc/>
-        public object Convert(object value, Type targetType, object parameter, string language)
+        public object? Convert(object? value, Type? targetType, object? parameter, string? language)
         {
             if (value is Task task)
             {
@@ -26,7 +28,7 @@ public object Convert(object value, Type targetType, object parameter, string la
         }
 
         /// <inheritdoc/>
-        public object ConvertBack(object value, Type targetType, object parameter, string language)
+        public object ConvertBack(object? value, Type? targetType, object? parameter, string? language)
         {
             throw new NotImplementedException();
         }

samples/MvvmSampleUwp/MvvmSampleUwp.csproj

@@ -18,7 +18,6 @@
     <ProjectTypeGuids>{A5A43C5B-DE2A-4C0C-9213-0A381AF9435A};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
     <WindowsXamlEnableOverview>true</WindowsXamlEnableOverview>
     <AppxPackageSigningEnabled>false</AppxPackageSigningEnabled>
-    <LangVersion>9.0</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|x86'">
     <DebugSymbols>true</DebugSymbols>

samples/MvvmSampleUwp/Services/SettingsService.cs

@@ -6,6 +6,8 @@
 using Windows.Foundation.Collections;
 using Windows.Storage;
 
+#nullable enable
+
 namespace MvvmSampleUwp.Services
 {
     /// <summary>
@@ -19,18 +21,18 @@ public sealed class SettingsService : ISettingsService
         private readonly IPropertySet SettingsStorage = ApplicationData.Current.LocalSettings.Values;
 
         /// <inheritdoc/>
-        public void SetValue<T>(string key, T value)
+        public void SetValue<T>(string key, T? value)
         {
             if (!SettingsStorage.ContainsKey(key)) SettingsStorage.Add(key, value);
             else SettingsStorage[key] = value;
         }
 
         /// <inheritdoc/>
-        public T GetValue<T>(string key)
+        public T? GetValue<T>(string key)
         {
-            if (SettingsStorage.TryGetValue(key, out object value))
+            if (SettingsStorage.TryGetValue(key, out object? value))
             {
-                return (T)value;
+                return (T)value!;
             }
 
             return default;