My logger. Requires ServiceStack.Text for the objectdump. DebugMode can be set on in the app startup, I usually do it on a Settings.app setting

BTLogger.cs

using System;
using System.Diagnostics;
using System.IO;
using ServiceStack.Text;

namespace BigTed.Utils
{
  public class BTLogger
	{
#if DEBUG
		public static bool DebugMode = true;
#else
		public static bool DebugMode = false;
#endif
		public static void Dump<T> (T o)
		{
			if (o == null) {
				Log ("LogObject was NULL");
				return;
			}

			try {
				string json = JsonSerializer.SerializeToString<T> (o);
				//string.Format gets funny with all the {}
				Log (json.Replace ("{", "{{").Replace ("}", "}}"));

			} catch (Exception ex) {
				Log ("error logging object");
				LogException (ex);
			}
		}

		static object loggingGate = new object ();

		public static void Log (string msg, params object[] param)
		{
			string res = msg;
			if (param.Length > 0) {
				res = string.Format (msg, param);
			}

			if (DebugMode) {
				Console.WriteLine (res);

				lock (loggingGate) {
					using (StreamWriter sw = File.AppendText(LogFilename)) {
						sw.WriteLine (DateTime.Now.ToString ("yyyyMMdd/HHmmss") + ": " + res);
						sw.Flush ();
						sw.Close ();
					}
				}

			}
		}

		public static string LogContent {
			get {
				lock (loggingGate) {
					if (!File.Exists (LogFilename))
						return "No log file present";
					return File.ReadAllText (LogFilename);
				}
			}
		}
		
		public static void LogException (Exception ex)
		{
			Log ("Exception: " + ex.ToString ());
			Log ("StackTrace: " + ex.StackTrace.ToString ());
			if (ex.InnerException != null) {
				LogException (ex.InnerException);
			}
		}

		public static void LogCurrentStack ()
		{
			StackTrace st = new StackTrace ();
			Log ("Stack trace: " + st.ToString ());
		}

		public static void CheckLogsForCleanup ()
		{

			if (File.Exists (LogFilename)) {
				FileInfo fi = new FileInfo (LogFilename);
				//BTLogger.Log ("Log file is {0:0} kb", fi.Length / 1024);
				if (fi.Length > (70 * 1024)) 
				{
					DeleteLogFile ();
					Log ("Log file purged - more than 70k");
				}
			}

		}

		public static void DeleteLogFile ()
		{
			lock (loggingGate) {
				if (File.Exists (LogFilename)) {
					File.Delete (LogFilename);
				}
			}
		}
		
		public static string LogFilename {
			get {
				return Path.Combine (Environment.GetFolderPath (Environment.SpecialFolder.MyDocuments), "bigted.log");
			}
		}
	}
}