How to use NSTimeZone -timeZoneWithName: with a city name from Rails ActiveSupport?

Question

If I only have the city name like Bangkok or Tokyo, how can I supply a timezone parameter in [NSTimeZone timeZoneWithName:@"Asia/Tokyo"] where it also has continent and slash in front of city?

I already tried [NSTimeZone timeZoneWithName:@"Tokyo"], it doesn't work.

Hlung · Accepted Answer · 2014-02-28T07:19:36.133

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Thanks for the answers guys, but it looks like those city names are just a format that Rails "ActiveSupport::TimeZone" uses. So I just have to map it back. The mapping is here -> http://api.rubyonrails.org/classes/ActiveSupport/TimeZone.html

It maps the timezone from Rails "ActiveSupport::TimeZone" format to another format that iOS uses (e.g. "International Date Line West" => "Pacific/Midway", "Midway Island" => "Pacific/Midway", "Samoa" => "Pacific/Pago_Pago", ... ).

I have created a plist file containing a NSDictionary property that can easily be used for mapping.

Edit: an updated version (with usage example) for Rails 3.2 (thanks RJ Regenold!)

edited Feb 28 '14 at 07:19

answered May 02 '12 at 10:42

Hlung

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Thanks for the plist. Very useful for Twitter user "time_zone" conversion. – DavidAWalsh Feb 03 '13 at 00:53
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Here is an updated version (with usage example) for Rails 3.2: https://gist.github.com/rjregenold/5243201 – RJ Regenold Mar 26 '13 at 04:48

score 13 · Answer 2 · answered Sep 19 '12 at 11:13

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You can see list of all timezone names.

NSLog(@"%@", [NSTimeZone knownTimeZoneNames]);

Hope this will be helpful for you.

answered Sep 19 '12 at 11:13

tagirkaZ

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score 5 · Answer 3 · answered Apr 30 '12 at 12:37

If they're all in Asia, why not use something like:

MYCITY=Tokyo
[NSTimeZone timeZoneWithName:@"Asia/$MYCITY"]

If you need more cities and timezones, you could create a static text list file based on all the time zones found at /usr/share/zoneinfo.

create file 'timezones.by.city.txt' with the following text. (Truncated here.)

"Asia/Aden"
"Asia/Almaty"
"Asia/Amman"
"Asia/Anadyr"
"Asia/Aqtau"
"Asia/Aqtobe"
"Asia/Ashgabat"
"Asia/Ashkhabad"
"Asia/Baghdad"
"Asia/Bahrain"
"Asia/Baku"
"Asia/Bangkok"
"Asia/Beirut"
"Asia/Bishkek"
... etc.
"US/Alaska"
"US/Aleutian"
"US/Arizona"
"US/Central"
"US/Eastern"
"US/East-Indiana"
"US/Hawaii"
"US/Indiana-Starke"
"US/Michigan"
"US/Mountain"
"US/Pacific"
"US/Pacific-New"
"US/Samoa"

Then:

MYCITY=Bangkok
MYTZ=`grep "$MYCITY" ./timezones.by.city.txt`
[df setTimeZone:[NSTimeZone timeZoneWithName:@"$MYTZ"]]

No, they are not all in Asia. And what is this `grep` thing? — Hlung, May 02 '12 at 08:38

score 1 · Answer 4 · edited May 02 '12 at 12:09

1

NSArray *zones = [NSTimeZone knownTimeZoneNames];

It returns all the set of timeszones supported by your system.

You have to setTime zone like below, which you have tried already.

[NSTimeZone timeZoneWithName:@"Asia/Tokyo"];

edited May 02 '12 at 12:09

Bill the Lizard

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answered Apr 30 '12 at 12:04

Allamaprabhu

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Yeah, I already know that. But I can't just change **Tokyo** to **Asia/Tokyo** because I also have names that are totally different from what I would get from `[NSTimeZone knownTimeZoneNames];`. – Hlung May 02 '12 at 10:48

score 0 · Answer 5 · answered Apr 30 '12 at 11:59

0

You may find the dataset and/or API from http://www.geonames.org/ useful in solving this sort of problem. They have the correct olsen timezone (which is what the 'Asia/Tokyo' is called) for a vast number of locations and you can either download and wrangle the data yourself, or use their API to get what you need.

answered Apr 30 '12 at 11:59

Roger

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Thanks, but unfortunately the timezone data I found there (http://download.geonames.org/export/dump/timeZones.txt) are in different names from the city names I have. So I cannot use it. I have posted an answer you can check it out :) – Hlung May 02 '12 at 10:46

score 0 · Answer 6 · edited Jul 24 '17 at 07:24

0

NSString * TimeZoneName=[[NSTimeZone localTimeZone]name];

edited Jul 24 '17 at 07:24

g00glen00b

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answered Jul 21 '17 at 13:10

Jignesh Radadiya

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How to use NSTimeZone -timeZoneWithName: with a city name from Rails ActiveSupport?

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