[Templates] Add comments to help developers publish MacCatalyst apps on App Store

dotnet/Templates/Microsoft.MacCatalyst.Templates/maccatalyst/csharp/Entitlements.plist

@@ -2,5 +2,14 @@
 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
     <dict>
+        <!-- app.sandbox is required by the App Store. See https://developer.apple.com/documentation/security/app_sandbox-->
+        <!-- <key>com.apple.security.app-sandbox</key>
+        <true/>
+        -->
+
+        <!-- When sandbox is enabled, this value is required if app was created with Blazor.-->
+        <!--<key>com.apple.security.network.client</key>
+        <true/>
+        -->
     </dict>
 </plist>

dotnet/Templates/Microsoft.MacCatalyst.Templates/maccatalyst/csharp/Info.plist

@@ -10,6 +10,15 @@
     <string>1.0</string>
     <key>CFBundleVersion</key>
     <string>1.0</string>
+    <!-- The App store requires that ITSAppUsesNonExemptEncryption to be set -->
+    <!-- Please consult https://developer.apple.com/documentation/bundleresources/information_property_list/itsappusesnonexemptencryption -->
+    <!-- <key>ITSAppUsesNonExemptEncryption</key> -->
+    <!-- Please indicate <true/> or <false/> here. -->
+
+    <!-- Specify the category for your app here. -->
+    <!-- Please consult https://developer.apple.com/documentation/bundleresources/information_property_list/lsapplicationcategorytype -->
+    <!-- <key>LSApplicationCategoryType</key> -->
+    <!-- <string>public.app-category.YOUR-CATEGORY-HERE</string> -->
     <key>UIDeviceFamily</key>
     <array>
         <integer>2</integer>

dotnet/Templates/Microsoft.MacCatalyst.Templates/maccatalyst/csharp/MacCatalystApp1.csproj

@@ -1,11 +1,53 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFramework>net7.0-maccatalyst</TargetFramework>
-    <RuntimeIdentifier>maccatalyst-x64</RuntimeIdentifier>
-    <RootNamespace Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">MacCatalystApp1</RootNamespace>
+    <!-- The default runtime is maccatalyst-x64, except in Release config, in which case the default is maccatalyst-x64;maccatalyst-arm64.
+         When specifying both architectures, use the plural <RuntimeIdentifiers> instead of the singular <RuntimeIdentifer>.
+         The App Store will NOT accept apps with ONLY maccatalyst-arm64 indicated;
+         either BOTH runtimes must be indicated or ONLY macatalyst-x64. -->
+    <!-- ex. <RuntimeIdentifiers>maccatalyst-x64;maccatalyst-arm64</RuntimeIdentifiers> -->
     <OutputType>Exe</OutputType>
     <Nullable>enable</Nullable>
     <ImplicitUsings>true</ImplicitUsings>
+    <RootNamespace Condition="'$(name)' != '$(name{-VALUE-FORMS-}safe_namespace)'">MacCatalystApp1</RootNamespace>
     <SupportedOSPlatformVersion>minOSVersion</SupportedOSPlatformVersion>
   </PropertyGroup>
+
+  <!-- Notes about the values set below:
+    1. For macOS it's possible to sign both the app bundle (EnableCodesigning=true) and the package (*.pkg) (EnablePackageSigning=true),
+       and these are signed separately and with different certificates.
+          CodesignKey: this is the signing key used for the app bundle
+          PackageSigningKey: this is the signing key used for the package
+    2. Publishing to the App Store requires signing both the app bundle and the package.
+          Must be 'Apple Distribution: ...' for the app bundle. Note that apps signed like this will not execute locally.
+          They have to be published to the App Store and then downloaded (Apple will resign the app with a different signing identity that allows for local execution).
+          Must be '3rd Party Mac Developer Installer: ...' for the pkg
+    3. Publishing outside of the App Store (i.e. only notarizing) requires:
+          Must be 'Developer ID Application: ...' for the app bundle
+          Must be 'Developer ID Installer: ...' for the pkg
+    4. During development, use the 'Apple Development: ...' signing key (typically to verify that the app works when is signed and entitlements are enforced).
+    5. Depending on the entitlements the app needs, a specific provisioning profile (CodesignProvision) might be needed.
+    6. UseHardenedRuntime must be set to true when app sandbox is enabled in Info.plist.
+    -->
+  <!--
+  For Debug: (Note: Replace placeholder information before building)
+  <PropertyGroup Condition="'$(Configuration)' == 'Debug'">
+    <CodesignKey>Apple Development: YOURNAME (*******)</CodesignKey>
+    <CodesignEntitlements>Entitlements.plist</CodesignEntitlements>
+    <CodesignProvision>YOUR PROFILE NAME</CodesignProvision>
+  </PropertyGroup>
+  -->
+  <!--
+  For Release: (Note: Replace placeholder information before building)
+  <PropertyGroup Condition="'$(Configuration)' == 'Release'">
+    <EnableCodeSigning>True</EnableCodeSigning>
+    <ProvisionType>Manual</ProvisionType>
+    <CreatePackage>true</CreatePackage>
+    <EnablePackageSigning>true</EnablePackageSigning>
+    <CodesignEntitlements>Entitlements.plist</CodesignEntitlements>
+    <CodesignKey>Apple Development: YOURNAME (*******)</CodesignKey>
+    <CodesignProvision>YOUR PROFILE NAME</CodesignProvision>
+    <PackageSigningKey>3rd Party Mac Developer Installer: YOURNAME (*******)</PackageSigningKey>
+    <UseHardenedRuntime>true</UseHardenedRuntime>
+  </PropertyGroup>-->
 </Project>