Code used to measure the network performance of an iPhone 5 while traveling around Seattle

AppDelegate.cs

using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Net;
using System.Threading;

using MonoTouch.Foundation;
using MonoTouch.UIKit;

using SQLite;

namespace LatencyMeasurement
{
	public class Measurement
	{
		[PrimaryKey, AutoIncrement]
		public int Id { get; set; }
		public DateTime RequestTime { get; set; }
		public DateTime ResponseTime { get; set; }
		public double Duration { get; set; }
		public string Error { get; set; }
		public int ResponseContentLength { get; set; }
	}

	[Register ("AppDelegate")]
	public class AppDelegate : UIApplicationDelegate
	{
		const string TestUrl = "https://news.google.com";

		const int TimeoutMillis = 20 * 1000;

		SQLiteConnection db;

		UIWindow window;
		UILabel label;
		NSTimer timer;

		public override bool FinishedLaunching (UIApplication app, NSDictionary options)
		{
			app.IdleTimerDisabled = true;

			var dbPath = Path.Combine (
				Environment.GetFolderPath (Environment.SpecialFolder.MyDocuments),
				"Measurements.db");
			Console.WriteLine (dbPath);

			db = new SQLiteConnection (dbPath, true);
			db.CreateTable<Measurement> ();

			var vc = new UIViewController ();
			label = new UILabel (new RectangleF (0, 100, 320, 60)) {
				Font = UIFont.BoldSystemFontOfSize (50),
				AdjustsFontSizeToFitWidth = true,
				Text = "Hello",
				TextAlignment = UITextAlignment.Center,
			};
			vc.View.AddSubview (label);

//			Dump ();

			timer = NSTimer.CreateRepeatingScheduledTimer (30, HandleTimer);

			window = new UIWindow (UIScreen.MainScreen.Bounds);
			window.RootViewController = vc;
			window.MakeKeyAndVisible ();
			
			return true;
		}

		void Dump ()
		{
			using (var w = new StreamWriter ("/Users/fak/Desktop/Results.csv")) {

				var ms = db.Table<Measurement> ().OrderBy (x => x.RequestTime).Skip (2);

				w.WriteLine ("Start Time,Duration,Content Length,Error");

				foreach (var m in ms) {
					w.WriteLine (
						"{0},{1},{2},{3}",
						m.RequestTime.ToLocalTime (),
						m.Duration,
						m.ResponseContentLength,
						m.Error);
				}
			}
		}

		void Display (string format, params object[] args)
		{
			BeginInvokeOnMainThread (() => {
				label.Text = string.Format (format, args);
			});
		}

		void HandleTimer ()
		{
			ThreadPool.QueueUserWorkItem (o => {

				var buffer = new byte[16*1024];
				var length = 0;

				Display ("Requesting...");

				var req = (HttpWebRequest)WebRequest.Create (TestUrl);
				var m = new Measurement ();
				m.RequestTime = DateTime.UtcNow;

				try {
					req.Timeout = TimeoutMillis;
					req.ReadWriteTimeout = TimeoutMillis;
					req.KeepAlive = false;

					var res = req.GetResponse ();

					Display ("Receiving...");

					var n = 0;

					using (var s = res.GetResponseStream ()) {
						for (;;) {
							n = s.Read (buffer, 0, buffer.Length);
							if (n <= 0) {
								break;
							}
							else {
								length += n;
							}
						}
					}

					m.Error = "";
				} catch (Exception ex) {
					m.Error = ex.GetType () + ": " + ex.Message;
				}

				m.ResponseContentLength = length;
				m.ResponseTime = DateTime.UtcNow;
				m.Duration = (m.ResponseTime - m.RequestTime).TotalSeconds;
				if (m.Duration <= 1e-3) {
					m.Duration = 1e-3;
				}

				db.Insert (m);

				Display ("{0:#,##0} B/s", m.ResponseContentLength / m.Duration);
			});
		}

		static void Main (string[] args)
		{
			UIApplication.Main (args, null, "AppDelegate");
		}
	}
}