// 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 Program

{

// Defined in main.m

[DllImport("__Internal")]

private static extern void ios_set_text(string value);

[DllImport("__Internal")]

unsafe private static extern void ios_register_button_click(delegate* unmanaged<void> callback);

private static int counter = 0;

// Called by native code, see main.m

[UnmanagedCallersOnly]

private static void OnButtonClick()

{

ios_set_text("OnButtonClick! #" + counter++);

}

#if CI_TEST

public static async Task<int> Main(string[] args)

#else

public static async Task Main(string[] args)

#endif

{

unsafe {

// Register a managed callback (will be called by UIButton, see main.m)

delegate* unmanaged<void> unmanagedPtr = &OnButtonClick;

ios_register_button_click(unmanagedPtr);

}

const string msg = "Hello World!\n.NET 5.0";

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!");

#if CI_TEST

await Task.Delay(5000);

return 42;

#else

await Task.Delay(-1);

#endif

}

}