NSDate获取本地时间

Question

I build app that get date string(date in french time) from a database. after i get the string i convert it to nsdate:

NSString *dateStr = "20/3/2016 21:00 +0000";

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"dd/MM/yyyy HH:mm zzz"];
NSTimeZone *gmt = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
[dateFormatter setTimeZone:gmt];
self.date = [dateFormatter dateFromString:dateStr];

Into self.date i get(if i print the object) :

2016-06-10 21:00:00 +0000

But when i try to convert it to local time:

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"HH:mm"];
NSString *time = [formatter stringFromDate:cellItem.date];

I get a different time: 00:00

Any idea what can be the problem?

Answer 1

The default time zone for an NSDateFormatter is the time zone of the device, and as you didn't set it explicitly in the second formatter, that is what will be used.

Use the first formatter for both jobs or set it explicitly as you did in the first formatter:

NSTimeZone *gmt = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
[dateFormatter setTimeZone:gmt];

Also a note on:

Into self.date i get (if i print the object)

If you are using NSLog() or the debugger to view an NSDate object, it will use [NSDate description] to generate the string, which will always use the GMT time zone. This constantly trips people up.