Xamarin apps can be developed using C#, F#, and Visual Basic.
Example:
C#:
using System;
using Xamarin.Forms;
namespace AppName
{
public class App : Application
{
public App()
{
// The root page of your application
MainPage = new MainPage();
}
protected override void OnStart()
{
// Handle when your app starts
}
protected override void OnSleep()
{
// Handle when your app sleeps
}
protected override void OnResume()
{
// Handle when your app resumes
}
}
}