C# 如何在xamarin.ios的body中使用post方法加载web视图？

我想在加载web视图时将我的objective-c代码转换为xamarin.ios中的c#无法与服务器进行通信web视图显示为空白屏幕

目标c代码：

NSData *myRequestData = [NSData dataWithBytes: [encryptedStr UTF8String] length: [encryptedStr length]];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] initWithURL: [NSURL URLWithString: urlAsString]];
[request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"content-type"];
[request setValue:urlAsString forHTTPHeaderField:@"Referer"];
[request setHTTPMethod: @"POST"];
[request setHTTPBody: myRequestData];
NSLog(@"HTTPBody:%@",request.HTTPBody);
NSLog(@"myRequestData:%@",myRequestData);
[_viewWeb loadRequest:request];

//This is  how i converted  above objective-c code to the  c# code for xamarin.ios

NSString pathurl = new NSString(AppConstants.TRANS_URL);
        pathurl = pathurl.CreateStringByAddingPercentEscapes(NSStringEncoding.ISOLatin1);
        NSUrl urls = NSUrl.FromString(pathurl);

        byte[] st2 = System.Text.Encoding.UTF8.GetBytes(postparam);
        // Initialize unmanaged memory to hold the array.
        int size = Marshal.SizeOf(st2[0]) * st2.Length;
        IntPtr pnt = Marshal.AllocHGlobal(size);
        try
        {
            // Copy the array to unmanaged memory.
            Marshal.Copy(st2, 0, pnt, st2.Length);
            // Copy the unmanaged array back to another managed array.
            byte[] managedArray2 = new byte[st2.Length];
            Marshal.Copy(pnt, managedArray2, 0, st2.Length);
            Console.WriteLine("The array was copied to unmanaged memory and back.");
        }
        finally
        {
            // Free the unmanaged memory.
            Marshal.FreeHGlobal(pnt);
        }

        NSData myRequestData = NSData.FromBytes(pnt,(nuint) postparam.Length);
        var dictionnary = NSDictionary.FromObjectAndKey(new NSString(AppConstants.TRANS_URL), new NSString("Referer"));
        var req = new NSMutableUrlRequest(urls);
        req["Content-Type"] = "application/x-www-form-urlencoded charset=utf-8";
        req.HttpMethod = "POST";
        req.Headers = dictionnary;
        webView.LoadRequest(req);

我无法与服务器通信并加载web视图

先谢谢你