使用PCL Xamarin Forms将图像上载到FTP服务器

Question

我是Xamarin和C＃世界的新手，我正在尝试将图像上传到FTP服务器。我看到FtpWebRequest类做到这一点，但我没有做对，我不知道如何注入plataform特定代码，我甚至不知道它是什么意思，已经看过这个视频（https://www.youtube.com/watch?feature=player_embedded&v=yduxdUCKU1c）但我不知道看看如何使用它来创建FtpWebRequest类并上传图像。

我看到这个代码（这里：https://forums.xamarin.com/discussion/9052/strange-behaviour-with-ftp-upload）发送图片，我无法使用它。

public void sendAPicture(string picture)
{

    string ftpHost = "xxxx";

    string ftpUser = "yyyy";

    string ftpPassword = "zzzzz";

    string ftpfullpath = "ftp://myserver.com/testme123.jpg";

    FtpWebRequest ftp = (FtpWebRequest)FtpWebRequest.Create(ftpfullpath);

    //userid and password for the ftp server  

    ftp.Credentials = new NetworkCredential(ftpUser, ftpPassword);

    ftp.KeepAlive = true;
    ftp.UseBinary = true;
    ftp.Method = WebRequestMethods.Ftp.UploadFile;

    FileStream fs = File.OpenRead(picture);

    byte[] buffer = new byte[fs.Length];
    fs.Read(buffer, 0, buffer.Length);

    fs.Close();

    Stream ftpstream = ftp.GetRequestStream();
    ftpstream.Write(buffer, 0, buffer.Length);
    ftpstream.Close();
    ftpstream.Flush();

    //  fs.Flush();

}

我没有类型FileStream，WebRequestMethods和File，我的FtpWebRequest类也没有“KeepAlive”，“UseBinary”和“GetRequestStream”方法，而我的Stream类没有“Close”方法。

我的FtpWebRequest类：

public sealed class FtpWebRequest：WebRequest {public override string ContentType {get {throw new NotImplementedException（）; }

    set
    {
        throw new NotImplementedException();
    }
}

public override WebHeaderCollection Headers
{
    get
    {
        throw new NotImplementedException();
    }

    set
    {
        throw new NotImplementedException();
    }
}

public override string Method
{
    get
    {
        throw new NotImplementedException();
    }

    set
    {
        throw new NotImplementedException();
    }
}

public override Uri RequestUri
{
    get
    {
        throw new NotImplementedException();
    }
}

public override void Abort()
{
    throw new NotImplementedException();
}

public override IAsyncResult BeginGetRequestStream(AsyncCallback callback, object state)
{
    throw new NotImplementedException();
}

public override IAsyncResult BeginGetResponse(AsyncCallback callback, object state)
{
    throw new NotImplementedException();
}

public override Stream EndGetRequestStream(IAsyncResult asyncResult)
{
    throw new NotImplementedException();
}

public override WebResponse EndGetResponse(IAsyncResult asyncResult)
{
    throw new NotImplementedException();
}

}

（我知道，我没有写任何东西，只按ctrl +。因为我不知道该写些什么）

有没有人能为我提供FtpWebRequest类的完整示例？我只发现上面这个使用的类。