Update NSUrlSessionHandler to handle nint StatusCode

src/ModernHttpClient/iOS/NSUrlSessionHandler.cs

@@ -2,7 +2,6 @@ using System;
 using System.Net.Http;
 using System.Threading.Tasks;
 using System.Threading;
-using MonoTouch.Foundation;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -11,6 +10,12 @@ using System.Net.Security;
 using System.Security.Cryptography.X509Certificates;
 using System.Text.RegularExpressions;
 
+#if UNIFIED
+using Foundation;
+#else
+using MonoTouch.Foundation;
+#endif
+
 namespace ModernHttpClient
 {
     class InflightOperation
@@ -149,7 +154,9 @@ namespace ModernHttpClient
 
                     content.Progress = data.Progress;
 
-                    var ret = new HttpResponseMessage((HttpStatusCode)resp.StatusCode) {
+                    // NB: The double cast is because of a Xamarin compiler bug
+                    int status = (int)resp.StatusCode;
+                    var ret = new HttpResponseMessage((HttpStatusCode)status) {
                         Content = content,
                         RequestMessage = data.Request,
                     };