How do you return the system time zone as a string? - objective-c

Question

I have an app where I set time zones for various cities around the globe. I have no problem doing this and it works great. When the app first loads, it finds your current location (lat & long) and sets the time zone using the device default time zone. I need to return the default time zone in a string, so I can display it. I don't want "GMT" or "EDT", I would like it in the format of "America/New_York" or 'Europe/London". Any ideas?

Answer 1

It sounds like you want this:
NSString *timeZoneName = [[NSTimeZone localTimeZone] name];
That returns "America/New_York" for me, here in the EST time zone.
Or given any NSTimeZone *tz you can get its [tz name], which is the conventional name you are looking for (e.g. "Asia/Tokyo" or "Europe/London".
Look at +[NSTimeZone knownTimeZoneName] for a list of possible names.
I hope that helps.

Answer 2

I don't think there is an object that automatically correlates the time zone to a physical place.
I see you've tagged this objective-c, but in C# you could do something simple like this:
public Enum TimeZone
{
[Description("New York")]
EDT,
[Description("Los Angeles")]
PST
}
public static string GetDescription(Enum value)
{
FieldInfo fi= value.GetType().GetField(value.ToString());
DescriptionAttribute[] attributes = (DescriptionAttribute[])fi.GetCustomAttributes(typeof(DescriptionAttribute), false);
return (attributes.Length>0)?attributes[0].Description:value.ToString();
}
i'm not sure how easily portable this is to objective-c, and it does require using the reflection library in C#.

Answer 3

Well, you're making the assumption that EDT is the same time zone as America/New_York. It isn't. :) Yes, they're the same UTC offset, but as far as your system is concerned, they are defined independently. There's no strong association between them that Cocoa knows about.
As well, if the user gives you EDT, do you return New_York? Toronto? Panama? There's not a 1:1 correspondence. Oh, and: EDT isn't even unique to a single UTC offset. Australian Eastern Daylight Time is also abbreviated EDT, I'm told by the Cocoa docs.
There is a [NSTimeZone abbreviationDictionary] map between abbreviations and long names, but again, they're arbitrarily chosen when there's more than one association (such as New York and Panama.)
What is it you're trying to accomplish in a broader sense? What's your goal? Tell us and we may be able to suggest an alternate way to achieve it. :)