[mono] Add iOS app sample using mono runtime

core/mono-samples/README.md

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+# Sample .NET apps using the Mono runtime
+
+This folder contains sample code demonstrating how to build mobile (iOS, Android, Browser WebAssembly) apps with the mono runtime. The requirements for each sample can be found within the corresponding folder, and each sample can be ran using `dotnet publish`.
+
+## Prerequisites
+
+.NET SDK version 6.0.100-alpha.1.20531.2 is needed to run these samples. To install a specific version of the dotnet sdk, download the latest stable version of the dotnet-install script:
+
+- Bash (Linux/macOS): <https://dot.net/v1/dotnet-install.sh>
+- PowerShell (Windows): <https://dot.net/v1/dotnet-install.ps1>
+
+Install version .NET version **6.0.100-alpha.1.20531.2**:
+
+```bash
+./dotnet-install.sh --version 6.0.100-alpha.1.20531.2
+```
+
+```powershell
+./dotnet-install.ps1 -Version 6.0.100-alpha.1.20531.2
+```
+
+For more information, see [dotnet-install script reference](https://docs.microsoft.com/dotnet/core/tools/dotnet-install-script)

core/mono-samples/iOS/NuGet.config

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+<?xml version="1.0" encoding="utf-8"?>
+<configuration>
+  <packageSources>
+    <add key="dotnet6" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet6/nuget/v3/index.json" />
+  </packageSources>
+</configuration>

core/mono-samples/iOS/README.md

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+---
+languages:
+- csharp
+products:
+- dotnet-core
+page_type: sample
+name: "iOS Sample: Simple greeting and counter (C#)"
+description: "An iOS application that contains an example of embedding the mono runtime to invoke unmanaged code with C#."
+urlFragment: "mono-ios-csharp"
+---
+
+# iOS Sample: Simple greeting and counter (C#)
+
+In this sample, the mono runtime is used to invoke Objective-c unmanaged code (main.m) from the C# managed side (iOSSampleApp.cs) and vice versa. With the sample running, you can enter your name and click the corresponding button to modify the greeting message as well as clicking a button to increment a counter.
+
+> [!NOTE]
+> The purpose of this sample is to demonstrate the concept of building an iOS application on top of the mono runtime. The mono runtime headers should be supplied through the build process.
+
+## Sample Prerequisites
+
+This sample will only run on macOS as it requires Xcode and an iOS simulator.
+
+- Xcode: Any version should work with this sample (download Xcode at <https://developer.apple.com/xcode/>).
+- iOS simulator 8.0 or greater.
+- .NET sdk 6.0.100-alpha.1.20531.2 (Installation instructions in parent directory).
+
+To install a specific version of the dotnet sdk, download the latest stable version of the dotnet-install script:
+
+- Bash (Linux/macOS): <https://dot.net/v1/dotnet-install.sh>
+- PowerShell (Windows): <https://dot.net/v1/dotnet-install.ps1>
+
+Install version .NET version **6.0.100-alpha.1.20531.2**:
+
+```bash
+./dotnet-install.sh --version 6.0.100-alpha.1.20531.2
+```
+
+```powershell
+./dotnet-install.ps1 -Version 6.0.100-alpha.1.20531.2
+```
+
+> [!NOTE]
+> Modify `IosSimulator` under target `BuildAppBundle` from `iPhone 11` to your simulator's device name.
+
+## Building the sample
+
+The source code includes an MSBuild project file for C# (a _.csproj_ file) that targets .NET 6.0. After downloading the _.zip_ file, be sure to have the iOS simulator open and modify `iPhone 11` in `iOSSampleApp.csproj` to the simulator's name. To run the sample, open the command line, navigate to the downloaded folder, and run `dotnet publish`.

core/mono-samples/iOS/global.json

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+{
+  "sdk": {
+    "version": "6.0.100-alpha.1.20531.2",
+    "rollForward": "major",
+    "allowPrerelease": true
+  }
+}

core/mono-samples/iOS/iOSSampleApp.cs

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+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Runtime.InteropServices;
+
+public static class iOSSampleApp
+{
+    // Defined in main.m
+    [DllImport("__Internal")]
+    private extern static void ios_set_text(string value);
+
+    [DllImport("__Internal")]
+    private extern static void ios_greet_name(string value);
+
+    [DllImport("__Internal")]
+    private extern static void ios_register_counter_increment(Action action);
+
+    [DllImport("__Internal")]
+    private extern static void ios_register_name_greet(Action<string> action);
+
+    private static int counter = 1;
+
+    // Called by native code, see main.m
+    private static void IncrementCounter()
+    {
+        ios_set_text($"Clicked {counter++} times!");
+    }
+
+    private static void GreetName(string name)
+    {
+        ios_greet_name(name);
+    }
+
+    public static async Task Main(string[] args)
+    {
+        // Register a managed callback (will be called by UIButton, see main.m)
+        // Also, keep the handler alive so GC won't collect it.
+        ios_register_counter_increment(IncrementCounter);
+        ios_register_name_greet(GreetName);
+
+        const string msg = "Hello World!";
+        for (int i = 0; i < msg.Length; i++)
+        {
+            // a kind of an animation
+            ios_set_text(msg.Substring(0, i + 1));
+            await Task.Delay(100);
+        }
+
+        Console.WriteLine("Done!");
+        await Task.Delay(-1);
+    }
+}

core/mono-samples/iOS/iOSSampleApp.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net6.0</TargetFramework>
+    <TargetArchitecture>x64</TargetArchitecture>
+    <RuntimeIdentifier>ios-$(TargetArchitecture)</RuntimeIdentifier>
+    <OutputType>Exe</OutputType>
+    <PublishTrimmed>True</PublishTrimmed>
+    <TrimMode>link</TrimMode>
+    <Configuration>Release</Configuration>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Runtime.iOS.Sample.Mono" Version="6.0.0-*" GeneratePathProperty="true" />
+  </ItemGroup>
+
+  <UsingTask TaskName="AppleAppBuilderTask"
+             AssemblyFile="$(PkgMicrosoft_NET_Runtime_iOS_Sample_Mono)\tools\net6.0\AppleAppBuilder.dll" />
+
+  <Target Name="BuildAppBundle" AfterTargets="Publish">
+    <PropertyGroup>
+      <AppDir>$(MSBuildThisFileDirectory)$(PublishDir)</AppDir>
+      <IosSimulator Condition="'$(TargetArchitecture)' == 'x64' or '$(TargetArchitecture)' == 'x86'">iPhone 11</IosSimulator>
+      <Optimized Condition="'$(Configuration)' == 'Release'">True</Optimized>
+    </PropertyGroup>
+
+    <ItemGroup>
+      <BundleAssemblies Include="$(AppDir)\*.dll" />
+    </ItemGroup>
+
+    <AppleAppBuilderTask
+      ProjectName="HelloiOS"
+      AppDir="$(AppDir)"
+      MonoRuntimeHeaders="%(ResolvedRuntimePack.PackageDirectory)\runtimes\$(RuntimeIdentifier)\native\include\mono-2.0"
+      MainLibraryFileName="$(MSBuildThisFileName).dll"
+      Assemblies="@(BundleAssemblies)"
+      OutputDirectory="$(AppDir)\app"
+      Optimized="$(Optimized)"
+      Arch="$(TargetArchitecture)"
+      BuildAppBundle="True"
+      GenerateXcodeProject="True"
+      NativeMainSource="$(MSBuildThisFileDirectory)main.m">
+      <Output TaskParameter="AppBundlePath" PropertyName="AppBundlePath" />
+      <Output TaskParameter="XcodeProjectPath" PropertyName="XcodeProjectPath" />
+    </AppleAppBuilderTask>
+
+    <Message Importance="High" Text="Xcode: $(XcodeProjectPath)" />
+    <Message Importance="High" Text="App:   $(AppBundlePath)" />
+    <Message Importance="High" Text="Restarting device" />
+    <Exec Condition="'$(IosSimulator)' != ''" Command="xcrun simctl shutdown &quot;$(IosSimulator)&quot;" ContinueOnError="WarnAndContinue" />
+    <Exec Condition="'$(IosSimulator)' != ''" Command="xcrun simctl boot &quot;$(IosSimulator)&quot;" />
+    <Exec Condition="'$(IosSimulator)' != ''" Command="open -a Simulator" />
+    <Message Importance="High" Text="Installing application" />
+    <Exec Condition="'$(IosSimulator)' != ''" Command="xcrun simctl install &quot;$(IosSimulator)&quot; $(AppBundlePath)" />
+    <Message Importance="High" Text="Launching application" />
+    <Exec Condition="'$(IosSimulator)' != ''" Command="xcrun simctl launch --console booted net.dot.HelloiOS" />
+  </Target>
+</Project>