Open pdf file downloaded from mvc web api in xamarin.forms

Question

I have a simple question but I'm unable to find a solution for it. Well I have a web api as the server. On the other side I have a xamarin forms client. I read the pdf in a httresponsemessage as a stream and return it to the client.

Here is my web api mvc controller method:

 [Route("pdf")]
        public HttpResponseMessage GetPDF()
        {
            //StreamContent pdfContent =  PdfGenerator.GeneratePdf();

            HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
            response.Content = new StreamContent(new MemoryStream(File.ReadAllBytes(@"D:\TestDocs\Invoice 6134034_27032017152428..pdf")));
            response.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment");
            response.Content.Headers.ContentDisposition.FileName = "PDFName.pdf";

            return response;
        }

In my xamarin app I have this code:

  public static HttpResponseMessage DownloadPDF(string token, Uri uri)
        {
            using (var client = new HttpClient())
            {
                if (!string.IsNullOrEmpty(token))
                {
                    client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue(BEARER, token);
                }

                return client.GetAsync(uri).Result;
            }
        }

But now I'm stuck. How can I open this pdf in my xamarin.forms app? I'm using a shared project.

Any help is appreciated.