System.TimeZoneInfo.GetSystemTimeZones C# (CSharp) Method

		public static ReadOnlyCollection<TimeZoneInfo> GetSystemTimeZones ()
		{
			if (systemTimeZones == null) {
				var tz = new List<TimeZoneInfo> ();
				GetSystemTimeZonesCore (tz);
				Interlocked.CompareExchange (ref systemTimeZones, new ReadOnlyCollection<TimeZoneInfo> (tz), null);
			}

			return systemTimeZones;
		}