Attach IDisposable to a Lifecycle.Event in Xamarin.Android

AutoDispose.md

Usage:

// Inside a Fragment or Activity
IDisposable.AutoDispose(this, Lifecycle.Event.OnDestroy);

// One more option for a Fragment
IDisposable.AutoDispose(ViewLifecycleOwner, Lifecycle.Event.OnDestroy);

AutoDisposeExtensions.cs

using AndroidX.Lifecycle;
using System;
using System.Collections.Generic;
using System.Linq;

namespace AutoDispose
{
    public static class AutoDisposeExtensions
    {
        public static IDisposable AutoDispose(this IDisposable self, ILifecycleOwner lifecycleOwner, Lifecycle.Event disposeEvent)
        {
            return AutoDispose(self.Yield(), lifecycleOwner, disposeEvent).First();
        }

        public static T AutoDispose<T>(this T self, ILifecycleOwner lifecycleOwner, Lifecycle.Event disposeEvent) where T : IEnumerable<IDisposable>
        {
            var observer = new LifecycleEventObserver();
            observer.StateChanged += (s, e) =>
            {
                if (e == disposeEvent)
                {
                    foreach (var disposable in self)
                    {
                        disposable.Dispose();
                    }
                    s.Lifecycle.RemoveObserver(observer);
                }
            };

            lifecycleOwner.Lifecycle.AddObserver(observer);

            return self;
        }
        
        private static IEnumerable<T> Yield<T>(this T item)
        {
            yield return item;
        }
    }
}

LifecycleEventObserver.cs

using AndroidX.Lifecycle;
using System;

namespace AutoDispose
{
    public class LifecycleEventObserver : Java.Lang.Object, ILifecycleEventObserver
    {
        public event Action<ILifecycleOwner, Lifecycle.Event> StateChanged = (_, __) => { };

        public void OnStateChanged(ILifecycleOwner source, Lifecycle.Event e)
        {
            StateChanged.Invoke(source, e);
        }
    }
}