Enable Nullability for Android, GTK, iOS, Tizen, UWP & WPF Sample Projects

samples/XCT.Sample.Android/SplashActivity.cs

@@ -9,7 +9,7 @@ namespace Xamarin.CommunityToolkit.Sample.Droid
 	[Activity(Label = "XamarinCommunityToolkitSample", Icon = "@mipmap/icon", Theme = "@style/SplashTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
 	public class SplashActivity : AppCompatActivity
 	{
-		protected override void OnCreate(Bundle savedInstanceState)
+		protected override void OnCreate(Bundle? savedInstanceState)
 		{
 			base.OnCreate(savedInstanceState);
 			var intent = new Intent(this, typeof(MainActivity));

samples/XCT.Sample.Android/Xamarin.CommunityToolkit.Sample.Android.csproj

@@ -22,6 +22,9 @@
     <AndroidHttpClientHandlerType>Xamarin.Android.Net.AndroidClientHandler</AndroidHttpClientHandlerType>
     <NuGetPackageImportStamp>
     </NuGetPackageImportStamp>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>nullable</WarningsAsErrors>
+    <LangVersion>latest</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>

samples/XCT.Sample.GTK/Xamarin.CommunityToolkit.Sample.GTK.csproj

@@ -13,6 +13,9 @@
     <FileAlignment>512</FileAlignment>
     <Deterministic>true</Deterministic>
     <TargetFrameworkProfile />
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>nullable</WarningsAsErrors>
+    <LangVersion>latest</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <DebugSymbols>true</DebugSymbols>

samples/XCT.Sample.Tizen/Xamarin.CommunityToolkit.Sample.Tizen.csproj

@@ -3,6 +3,9 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFramework>tizen40</TargetFramework>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>nullable</WarningsAsErrors>
+    <LangVersion>latest</LangVersion>
   </PropertyGroup>
 
   <ItemGroup>

samples/XCT.Sample.UWP/Xamarin.CommunityToolkit.Sample.UWP.csproj

@@ -18,6 +18,9 @@
     <FileAlignment>512</FileAlignment>
     <ProjectTypeGuids>{A5A43C5B-DE2A-4C0C-9213-0A381AF9435A};{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}</ProjectTypeGuids>
     <AppxPackageSigningEnabled>false</AppxPackageSigningEnabled>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>nullable</WarningsAsErrors>
+    <LangVersion>latest</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|ARM'">
     <DebugSymbols>true</DebugSymbols>

samples/XCT.Sample.WPF/Xamarin.CommunityToolkit.Sample.WPF.csproj

@@ -16,6 +16,9 @@
     <Deterministic>true</Deterministic>
     <NuGetPackageImportStamp>
     </NuGetPackageImportStamp>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>nullable</WarningsAsErrors>
+    <LangVersion>latest</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
     <PlatformTarget>AnyCPU</PlatformTarget>

samples/XCT.Sample.iOS/Renderers/NoLineNavigationRenderer.cs

@@ -25,8 +25,11 @@ public override void ViewWillAppear(bool animated)
 			// Newest iOS version fix - trycatch isn't optimal
 			try
 			{
-				NavigationBar.ScrollEdgeAppearance.ShadowImage = new UIKit.UIImage();
-				NavigationBar.ScrollEdgeAppearance.ShadowColor = null;
+				if (NavigationBar.ScrollEdgeAppearance != null)
+				{
+					NavigationBar.ScrollEdgeAppearance.ShadowImage = new UIKit.UIImage();
+					NavigationBar.ScrollEdgeAppearance.ShadowColor = null;
+				}
 			}
 			catch (Exception)
 			{

samples/XCT.Sample.iOS/Xamarin.CommunityToolkit.Sample.iOS.csproj

@@ -15,6 +15,9 @@
     <MtouchEnableSGenConc>true</MtouchEnableSGenConc>
     <MtouchHttpClientHandler>NSUrlSessionHandler</MtouchHttpClientHandler>
     <ProvisioningType>automatic</ProvisioningType>
+    <Nullable>enable</Nullable>
+    <WarningsAsErrors>nullable</WarningsAsErrors>
+    <LangVersion>latest</LangVersion>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|iPhoneSimulator' ">
     <DebugSymbols>true</DebugSymbols>

samples/XCT.Sample/Helpers/RelayCommand.cs

@@ -7,25 +7,21 @@ namespace Xamarin.CommunityToolkit.Sample
 {
 	public class RelayCommand : ICommand
 	{
-		readonly Action execute;
-		readonly Func<Task> asyncExecute;
+		readonly Action? execute;
+		readonly Func<Task>? asyncExecute;
+		readonly Func<bool>? canExecute;
 
-		Func<bool> canExecute;
 		int executingCount;
 
-		public RelayCommand(Action execute, Func<bool> canExecute = null)
+		public RelayCommand(Action execute, Func<bool>? canExecute = null)
 		{
-			if (execute == null)
-				throw new ArgumentNullException(nameof(execute));
-			this.execute = execute;
+			this.execute = execute ?? throw new ArgumentNullException(nameof(execute));
 			this.canExecute = canExecute;
 		}
 
-		protected RelayCommand(Func<Task> execute, Func<bool> canExecute = null) // This ctor is protected here and public in a derived class, to allow simple initialization like new RelayCommand(MyMethod) without errors due to ambiguity
+		protected RelayCommand(Func<Task> execute, Func<bool>? canExecute = null) // This ctor is protected here and public in a derived class, to allow simple initialization like new RelayCommand(MyMethod) without errors due to ambiguity
 		{
-			if (execute == null)
-				throw new ArgumentNullException(nameof(execute));
-			asyncExecute = execute;
+			asyncExecute = execute ?? throw new ArgumentNullException(nameof(execute));
 			this.canExecute = canExecute;
 		}
 
@@ -34,7 +30,7 @@ public RelayCommand(Action execute, Func<bool> canExecute = null)
 		/// </summary>
 		/// <param name="parameter">Ignored; this is the paremeterless command class</param>
 		/// <returns></returns>
-		public bool CanExecute(object parameter = null)
+		public bool CanExecute(object? parameter = null)
 		{
 			try
 			{
@@ -47,15 +43,12 @@ public bool CanExecute(object parameter = null)
 			}
 		}
 
-		public event EventHandler CanExecuteChanged;
+		public event EventHandler? CanExecuteChanged;
 
-		public void RaiseCanExecuteChanged()
-		{
-			CanExecuteChanged?.Invoke(this, EventArgs.Empty);
-		}
+		public void RaiseCanExecuteChanged() => CanExecuteChanged?.Invoke(this, EventArgs.Empty);
 
 		// Asynchronous command handling based on http://stackoverflow.com/a/31595509/6043538
-		public async void Execute(object parameter = null)
+		public async void Execute(object? parameter = null)
 		{
 			var couldExecuteBeforeExecute = CanExecute();
 			if (!couldExecuteBeforeExecute)
@@ -70,8 +63,10 @@ public async void Execute(object parameter = null)
 			{
 				if (execute != null)
 					execute();
-				else
+				else if (asyncExecute != null)
 					await asyncExecute();
+				else
+					throw new Exception("Execute is null");
 			}
 			catch (Exception ex)
 			{
@@ -89,31 +84,30 @@ public async void Execute(object parameter = null)
 
 	public class RelayCommandAsync : RelayCommand
 	{
-		public RelayCommandAsync(Func<Task> execute, Func<bool> canExecute = null)
-			: base(execute, canExecute) { } // This ctor is public here and protected in the base class, to allow simple initialization like new RelayCommandAsync(MyMethod) without errors due to ambiguity
+		public RelayCommandAsync(Func<Task> execute, Func<bool>? canExecute = null)
+			: base(execute, canExecute)
+		{
+			// This ctor is public here and protected in the base class, to allow simple initialization like new RelayCommandAsync(MyMethod) without errors due to ambiguity
+		}
 	}
 
 	public class RelayCommand<TParameter> : ICommand
 	{
-		readonly Action<TParameter> execute;
-		readonly Func<TParameter, Task> asyncExecute;
+		readonly Action<TParameter>? execute;
+		readonly Func<TParameter, Task>? asyncExecute;
+		readonly Func<TParameter?, bool>? canExecute;
 
-		Func<TParameter, bool> canExecute;
 		int executingCount;
 
-		public RelayCommand(Action<TParameter> execute, Func<TParameter, bool> canExecute = null)
+		public RelayCommand(Action<TParameter> execute, Func<TParameter?, bool>? canExecute = null)
 		{
-			if (execute == null)
-				throw new ArgumentNullException(nameof(execute));
-			this.execute = execute;
+			this.execute = execute ?? throw new ArgumentNullException(nameof(execute));
 			this.canExecute = canExecute;
 		}
 
-		protected RelayCommand(Func<TParameter, Task> execute, Func<TParameter, bool> canExecute = null) // This ctor is protected here and public in a derived class, to allow simple initialization like new RelayCommand(MyMethod) without errors due to ambiguity
+		protected RelayCommand(Func<TParameter, Task> execute, Func<TParameter?, bool>? canExecute = null) // This ctor is protected here and public in a derived class, to allow simple initialization like new RelayCommand(MyMethod) without errors due to ambiguity
 		{
-			if (execute == null)
-				throw new ArgumentNullException(nameof(execute));
-			asyncExecute = execute;
+			asyncExecute = execute ?? throw new ArgumentNullException(nameof(execute));
 			this.canExecute = canExecute;
 		}
 
@@ -122,11 +116,11 @@ public RelayCommand(Action<TParameter> execute, Func<TParameter, bool> canExecut
 		/// </summary>
 		/// <param name="parameter"></param>
 		/// <returns></returns>
-		public bool CanExecute(object parameter = null)
+		public bool CanExecute(object? parameter = null)
 		{
 			try
 			{
-				return canExecute != null ? canExecute((TParameter)parameter) : executingCount == 0;
+				return canExecute != null ? canExecute((TParameter?)parameter) : executingCount == 0;
 			}
 			catch (Exception ex)
 			{
@@ -135,12 +129,9 @@ public bool CanExecute(object parameter = null)
 			}
 		}
 
-		public event EventHandler CanExecuteChanged;
+		public event EventHandler? CanExecuteChanged;
 
-		public void RaiseCanExecuteChanged()
-		{
-			CanExecuteChanged?.Invoke(this, EventArgs.Empty);
-		}
+		public void RaiseCanExecuteChanged() => CanExecuteChanged?.Invoke(this, EventArgs.Empty);
 
 		// Asynchronous command handling based on http://stackoverflow.com/a/31595509/6043538
 		public async void Execute(object parameterAsObject)
@@ -159,13 +150,11 @@ public async void Execute(object parameterAsObject)
 				var parameter = (TParameter)parameterAsObject;
 
 				if (execute != null)
-				{
 					execute(parameter);
-				}
+				else if (asyncExecute != null)
+					await asyncExecute.Invoke(parameter);
 				else
-				{
-					await asyncExecute(parameter);
-				}
+					throw new Exception("Execute is null");
 			}
 			catch (Exception ex)
 			{
@@ -183,7 +172,10 @@ public async void Execute(object parameterAsObject)
 
 	public class RelayCommandAsync<TParameter> : RelayCommand<TParameter>
 	{
-		public RelayCommandAsync(Func<TParameter, Task> execute, Func<TParameter, bool> canExecute = null)
-			: base(execute, canExecute) { } // This ctor is public here and protected in the base class, to allow simple initialization like new RelayCommandAsync(MyMethod) without errors due to ambiguity
+		public RelayCommandAsync(Func<TParameter, Task> execute, Func<TParameter?, bool>? canExecute = null)
+			: base(execute, canExecute)
+		{
+			// This ctor is public here and protected in the base class, to allow simple initialization like new RelayCommandAsync(MyMethod) without errors due to ambiguity
+		}
 	}
 }

samples/XCT.Sample/Helpers/XLog.cs

@@ -13,7 +13,7 @@ namespace Xamarin.CommunityToolkit.Sample
 	/// </summary>
 	public static class XLog
 	{
-		static string rootFolderPattern = null;
+		static string? rootFolderPattern = null;
 #if WINDOWS_UWP
         static LoggingChannel loggingChannel;
 #endif
@@ -22,7 +22,7 @@ public static class XLog
 		/// Call this before logging starts.
 		/// </summary>
 		/// <param name="rootFolderPattern">Should match the top folder name(s) within the source control repository, e.g. @"\MobileRealtimePush\MobileRealtimePush\". Any folders before the first match of this pattern are omitted from the logged source file paths</param>
-		public static void Init(string rootFolderPattern = null)
+		public static void Init(string? rootFolderPattern = null)
 		{
 			XLog.rootFolderPattern = rootFolderPattern;
 #if WINDOWS_UWP
@@ -46,10 +46,10 @@ public static void Init(string rootFolderPattern = null)
 		/// <param name="sourceLineNumber">supplied by compiler, no need to specify in code unless you want to pass a deeper call context</param>
 		[Conditional("DEBUG")]
 		public static void Debug(
-			object data = null,
-			string tag = null,
-			[CallerMemberName] string memberName = null,
-			[CallerFilePath] string sourceFilePath = null,
+			object? data = null,
+			string? tag = null,
+			[CallerMemberName] string? memberName = null,
+			[CallerFilePath] string? sourceFilePath = null,
 			[CallerLineNumber] int sourceLineNumber = -1)
 		{
 			var message = FormatLogString(data, tag, memberName, sourceFilePath, sourceLineNumber);
@@ -75,10 +75,10 @@ public static void Debug(
 		/// <param name="sourceLineNumber">supplied by compiler, no need to specify in code unless you want to pass a deeper call context</param>
 		[Conditional("TRACE")]
 		public static void Trace(
-			object data = null,
-			string tag = null,
-			[CallerMemberName] string memberName = null,
-			[CallerFilePath] string sourceFilePath = null,
+			object? data = null,
+			string? tag = null,
+			[CallerMemberName] string? memberName = null,
+			[CallerFilePath] string? sourceFilePath = null,
 			[CallerLineNumber] int sourceLineNumber = -1)
 		{
 			var message = FormatLogString(data, tag, memberName, sourceFilePath, sourceLineNumber);
@@ -90,9 +90,9 @@ public static void Trace(
 #endif
 		}
 
-		public static string TruncateAt(this string s, int maxLength, string truncatedSuffix = "...") => s?.Length <= maxLength ? s : s.Substring(0, maxLength) + truncatedSuffix;
+		public static string TruncateAt(this string? s, int maxLength, string truncatedSuffix = "...") => s?.Length <= maxLength ? s : s?.Substring(0, maxLength) + truncatedSuffix;
 
-		static string FormatLogString(object data = null, string tag = null, string memberName = null, string sourceFilePath = null, int sourceLineNumber = -1)
+		static string FormatLogString(object? data, string? tag, string? memberName, string? sourceFilePath, int sourceLineNumber)
 		{
 			var line = new StringBuilder();
 
@@ -121,7 +121,7 @@ static string FormatLogString(object data = null, string tag = null, string memb
 				line.Append(dataString);
 			}
 
-			if (!string.IsNullOrEmpty(sourceFilePath))
+			if (sourceFilePath != null && !string.IsNullOrEmpty(sourceFilePath))
 			{
 				if (!string.IsNullOrEmpty(rootFolderPattern))
 				{

samples/XCT.Sample/Pages/Converters/BoolToObjectConverterPage.xaml.cs

@@ -1,15 +1,7 @@
-using System;
-using System.Collections.Generic;
-
-using Xamarin.Forms;
-
-namespace Xamarin.CommunityToolkit.Sample.Pages.Converters
+namespace Xamarin.CommunityToolkit.Sample.Pages.Converters
 {
-	public partial class BoolToObjectConverterPage 
+	public partial class BoolToObjectConverterPage
 	{
-		public BoolToObjectConverterPage()
-		{
-			InitializeComponent();
-		}
+		public BoolToObjectConverterPage() => InitializeComponent();
 	}
 }

samples/XCT.Sample/Pages/Converters/DoubleToIntConverterPage.xaml.cs

@@ -1,15 +1,7 @@
-using System;
-using System.Collections.Generic;
-
-using Xamarin.Forms;
-
-namespace Xamarin.CommunityToolkit.Sample.Pages.Converters
+namespace Xamarin.CommunityToolkit.Sample.Pages.Converters
 {
-	public partial class DoubleToIntConverterPage 
+	public partial class DoubleToIntConverterPage
 	{
-		public DoubleToIntConverterPage()
-		{
-			InitializeComponent();
-		}
+		public DoubleToIntConverterPage() => InitializeComponent();
 	}
 }

samples/XCT.Sample/Pages/Converters/EnumToBoolConverterPage.xaml.cs

@@ -1,10 +1,7 @@
-namespace Xamarin.CommunityToolkit.Sample.Pages.Converters
+namespace Xamarin.CommunityToolkit.Sample.Pages.Converters
 {
-	public partial class EnumToBoolConverterPage
-	{
-		public EnumToBoolConverterPage()
-		{
-			InitializeComponent();
-		}
-	}
+    public partial class EnumToBoolConverterPage
+    {
+        public EnumToBoolConverterPage() => InitializeComponent();
+    }
 }