Converting the date given from Apple receipts to a .net DateTime object

.NET has no built-in support for the zoneinfo/Olson/tz/IANA time zones (whatever you want to call them...) that are being used here. Fortunately, my Noda Time project does.

Here's some code using Noda Time 1.3.2 which successfully parses both the sample values you've given. The natural type for the data you've presented is ZonedDateTime, which is a date and time in a known time zone. Next, you could convert it to an OffsetDateTime, which is a bit like .NET's DateTimeOffset (which you can convert it to).

Personally I'd recommend trying to use the Noda Time types throughout your code - the aim of the project is to make date/time code a lot less fiddly and error-prone. If you really need to convert to the BCL types though, you can certainly do so.

using System;
using NodaTime;
using NodaTime.Text;

class Program
{
    private static readonly ZonedDateTimePattern ApplePattern =
        ZonedDateTimePattern.CreateWithInvariantCulture(
            "yyyy-MM-dd HH:mm:ss z", DateTimeZoneProviders.Tzdb);

    static void Main(string[] args)
    {
        ParseApple("2016-08-10 19:47:16 America/Los_Angeles");
        ParseApple("2016-08-11 02:42:16 Etc/GMT");
    }

    static void ParseApple(string text)
    {
        Console.WriteLine($"Parsing {text}");
        ParseResult<ZonedDateTime> result = ApplePattern.Parse(text);
        if (!result.Success)
        {
            Console.WriteLine($"Parse failed! {result.Exception.Message}");
            return;
        }
        ZonedDateTime zonedValue = result.Value;
        Console.WriteLine($"ZonedDateTime: {zonedValue}");
        // OffsetDateTime is a Noda Time type...
        OffsetDateTime offsetValue = zonedValue.ToOffsetDateTime();
        Console.WriteLine($"OffsetDateTime: {offsetValue}");
        // DateTimeOffset is the BCL type...
        DateTimeOffset dto = offsetValue.ToDateTimeOffset();
        Console.WriteLine($"DateTimeOffset: {dto}");
        Console.WriteLine();
    }
}

Output:

Parsing 2016-08-10 19:47:16 America/Los_Angeles
ZonedDateTime: 2016-08-10T19:47:16 America/Los_Angeles (-07)
OffsetDateTime: 2016-08-10T19:47:16-07
DateTimeOffset: 10/08/2016 19:47:16 -07:00

Parsing 2016-08-11 02:42:16 Etc/GMT
ZonedDateTime: 2016-08-11T02:42:16 Etc/GMT (+00)
OffsetDateTime: 2016-08-11T02:42:16Z
DateTimeOffset: 11/08/2016 02:42:16 +00:00