Implementing ModernHttpClient in MvvmCross - MvxFastFileDownloadRequest

MvxFastFileDownloadRequest

using System;
using Cirrious.MvvmCross.Plugins.DownloadCache;
using Cirrious.CrossCore.Core;
using System.Net.Http;
using ModernHttpClient;
using System.Threading.Tasks;
using System.IO;

namespace Ridland.MvvmCross.iOS.Plugins
{
    public class MvxFastFileDownloadRequest
    {
        public MvxFastFileDownloadRequest(string url, string downloadPath)
        {
            Url = url;
            DownloadPath = downloadPath;
        }

        public string DownloadPath { get; private set; }
        public string Url { get; private set; }

        public event EventHandler<MvxFileDownloadedEventArgs> DownloadComplete;
        public event EventHandler<MvxValueEventArgs<Exception>> DownloadFailed;

        HttpClient CreateClient()
        {
            return new HttpClient(new AFNetworkHandler());
        }

        public void Start()
        {
            var client = CreateClient();

            Task<HttpResponseMessage> result;

            result = client.GetAsync(Url);

            result.ContinueWith(res =>  {

                var httpResult = res.Result;
                httpResult.EnsureSuccessStatusCode(); 
                httpResult.Content.ReadAsStreamAsync()
                    .ContinueWith(HandleSuccess, 
                    TaskContinuationOptions.NotOnFaulted)
                        .ContinueWith(ae => FireDownloadFailed(ae.Exception), 
                                      TaskContinuationOptions.OnlyOnFaulted);

            }).ContinueWith(ae => FireDownloadFailed(ae.Exception), TaskContinuationOptions.OnlyOnFaulted);

        }

        private void HandleSuccess(Task<Stream> result)
        {
            try
            {
                var fileService = MvxFileStoreHelper.SafeGetFileStore();
                var tempFilePath = DownloadPath + ".tmp";

                using (result.Result)
                {
                    fileService.WriteFile(tempFilePath,
                                          (fileStream) =>
                    {
                        result.Result.CopyTo(fileStream);
                    });
                }
                fileService.TryMove(tempFilePath, DownloadPath, true);
            }
            catch (Exception exception)
            {
                FireDownloadFailed(exception);
                return;
            }

            FireDownloadComplete();
        }

        private void FireDownloadFailed(Exception exception)
        {
            var handler = DownloadFailed;
            if (handler != null)
                handler(this, new MvxValueEventArgs<Exception>(exception));
        }

        private void FireDownloadComplete()
        {
            var handler = DownloadComplete;
            if (handler != null)
                handler(this, new MvxFileDownloadedEventArgs(Url, DownloadPath));
        }
    }
}