Added `Run` target for Android

* split up `Directory.Build.targets` into iOS and Android files
* did this so the Android `Run` target won't interfere with iOS

Directory.Android.targets

@@ -0,0 +1,26 @@
+<Project>
+
+  <PropertyGroup>
+    <AssetTargetFallback>monoandroid10.0;monoandroid90;monoandroid81;monoandroid80;$(AssetTargetFallback)</AssetTargetFallback>
+    <!-- Workaround to skip a .NET 4.5 MSBuild task: https://github.com/xamarin/AndroidSupportComponents/blob/68d28bc676673ec45f7f5ea2462c10bed87e2a2a/source/buildtasks/support-vector-drawable/Support-Vector-Drawable-BuildTasks.csproj#L10 -->
+    <VectorDrawableCheckBuildToolsVersionTaskBeforeTargets />
+  </PropertyGroup>
+
+  <!-- NOTE: the target below is workarounds for $(AssetTargetFallback) usage -->
+  <!-- related: https://github.com/NuGet/docs.microsoft.com-nuget/issues/1955 -->
+  <Target
+    Name="FixAndroidNuGetAssemblies"
+    AfterTargets="ResolvePackageAssets"
+    Condition="'$(PkgXamarin_Forms)' != ''">
+    <ItemGroup>
+      <Reference Include="Xamarin.Forms.Platform"         HintPath="$(PkgXamarin_Forms)\lib\MonoAndroid10.0\Xamarin.Forms.Platform.dll" />
+      <Reference Include="Xamarin.Forms.Platform.Android" HintPath="$(PkgXamarin_Forms)\lib\MonoAndroid10.0\Xamarin.Forms.Platform.Android.dll" />
+      <Reference Include="FormsViewGroup"                 HintPath="$(PkgXamarin_Forms)\lib\MonoAndroid10.0\FormsViewGroup.dll" />
+      <RuntimeCopyLocalItems          Remove="$(PkgXamarin_Forms)\lib\netstandard2.0\Xamarin.Forms.Platform.dll" />
+      <ResolvedCompileFileDefinitions Remove="$(PkgXamarin_Forms)\lib\netstandard2.0\Xamarin.Forms.Platform.dll" />
+    </ItemGroup>
+  </Target>
+
+  <Target Name="Run" DependsOnTargets="StartAndroidActivity" />
+
+</Project>

Directory.Build.targets

@@ -1,33 +1,4 @@
 <Project>
-  <PropertyGroup Condition="'$(UsingAndroidNETSdk)' == 'true'">
-    <AssetTargetFallback>monoandroid10.0;monoandroid90;monoandroid81;monoandroid80;$(AssetTargetFallback)</AssetTargetFallback>
-    <!-- Workaround to skip a .NET 4.5 MSBuild task: https://github.com/xamarin/AndroidSupportComponents/blob/68d28bc676673ec45f7f5ea2462c10bed87e2a2a/source/buildtasks/support-vector-drawable/Support-Vector-Drawable-BuildTasks.csproj#L10 -->
-    <VectorDrawableCheckBuildToolsVersionTaskBeforeTargets />
-  </PropertyGroup>
-
-  <!-- NOTE: the target below is workarounds for $(AssetTargetFallback) usage -->
-  <!-- related: https://github.com/NuGet/docs.microsoft.com-nuget/issues/1955 -->
-  <Target
-    Name="FixAndroidNuGetAssemblies"
-    AfterTargets="ResolvePackageAssets"
-    Condition="'$(UsingAndroidNETSdk)' == 'true' and '$(PkgXamarin_Forms)' != ''">
-    <ItemGroup>
-      <Reference Include="Xamarin.Forms.Platform"         HintPath="$(PkgXamarin_Forms)\lib\MonoAndroid10.0\Xamarin.Forms.Platform.dll" />
-      <Reference Include="Xamarin.Forms.Platform.Android" HintPath="$(PkgXamarin_Forms)\lib\MonoAndroid10.0\Xamarin.Forms.Platform.Android.dll" />
-      <Reference Include="FormsViewGroup"                 HintPath="$(PkgXamarin_Forms)\lib\MonoAndroid10.0\FormsViewGroup.dll" />
-      <RuntimeCopyLocalItems          Remove="$(PkgXamarin_Forms)\lib\netstandard2.0\Xamarin.Forms.Platform.dll" />
-      <ResolvedCompileFileDefinitions Remove="$(PkgXamarin_Forms)\lib\netstandard2.0\Xamarin.Forms.Platform.dll" />
-    </ItemGroup>
-  </Target>
-
-  <Target
-    Name="SetiOSDefaultPublishProps"
-    BeforeTargets="PrepareForPublish"
-    Condition="$(RuntimeIdentifier.StartsWith('ios'))">
-    <PropertyGroup>
-      <PublishTrimmed>True</PublishTrimmed>
-      <MonoAOT>True</MonoAOT>
-      <UseAppHost>False</UseAppHost>
-    </PropertyGroup>
-  </Target>
+  <Import Condition="$(RuntimeIdentifier.StartsWith('android'))" Project="Directory.Android.targets" />
+  <Import Condition="$(RuntimeIdentifier.StartsWith('ios'))"     Project="Directory.iOS.targets" />
 </Project>

Directory.iOS.targets

@@ -0,0 +1,11 @@
+<Project>
+
+  <Target Name="SetiOSDefaultPublishProps" BeforeTargets="PrepareForPublish">
+    <PropertyGroup>
+      <PublishTrimmed>True</PublishTrimmed>
+      <MonoAOT>True</MonoAOT>
+      <UseAppHost>False</UseAppHost>
+    </PropertyGroup>
+  </Target>
+
+</Project>

README.md

@@ -10,6 +10,8 @@ Projects:
 * HelloiOS - a native Xamarin.iOS application
 * HelloForms, HelloForms.iOS, HelloForms.Android - a cross-platform Xamarin.Forms application
 
+### Android
+
 For example, to build the Android project:
 
     dotnet publish HelloAndroid\HelloAndroid.csproj
@@ -23,6 +25,14 @@ the `.csproj` or run:
 
     dotnet publish -t:Install HelloAndroid\HelloAndroid.csproj -r android.21-arm64
 
+To launch the app:
+
+    dotnet publish -t:Run HelloAndroid\HelloAndroid.csproj
+
+_This can also be done at the same time as `-t:Install`._
+
+### iOS
+
 To build the iOS project:
 
     dotnet publish HelloiOS/HelloiOS.csproj --self-contained