iOS convert server time to device local time? - ios

Question

I'm getting some issue to convert server time(argentina) to device local time.
here is my current code-
-(NSString *)getLocalTimeStringFrom:(NSString *)sourceTime
{
static NSDateFormatter* df = nil;
if (df == nil)
{
df = [[NSDateFormatter alloc]init];
}
df.dateFormat = #"HH:mm:ss";
NSDate* d = [df dateFromString:sourceTime];
NSTimeZone *sourceZone = [NSTimeZone timeZoneWithAbbreviation:#"ART"];//America/Argentina/Buenos_Aires (GMT-3)
NSTimeZone *localTimeZone = [NSTimeZone systemTimeZone]; //Asia/Kolkata (IST)
[df setTimeZone: sourceZone];
NSLog(#"sourceZone time is %#" , [df stringFromDate: d]);
[df setTimeZone: localTimeZone];
NSLog(#"local time is %#" , [df stringFromDate: d]);
NSLog(#"original time string was %#" , sourceTime);
return [df stringFromDate: d];
}
And here is the log if sourceTime string is 00:05:00
2015-09-28 15:04:24.118 DeviceP[230:17733] sourceZone time is 15:35:00
2015-09-28 15:04:24.121 DeviceP[230:17733] local time is 00:05:00
2015-09-28 15:04:33.029 DeviceP[230:17733] original time string was 00:05:00
note that i'm getting local time same as the time string i pass into the method. i looked various SO post like this and this.
Any help would be appreciated.

Answer 1

Since your time string is in ART, you should set the timezone of date formatter before making date from the string. Means like following
-(NSString *)getLocalTimeStringFrom:(NSString *)sourceTime
{
static NSDateFormatter* df = nil;
if (!df) {
df = [[NSDateFormatter alloc]init];
df.dateFormat = #"HH:mm:ss";
}
NSTimeZone *sourceZone = [NSTimeZone timeZoneWithAbbreviation:#"ART"];
[df setTimeZone: sourceZone];
NSDate *ds = [df dateFromString:sourceTime];
NSLog(#"sourceZone time is %#" , [df stringFromDate: ds]);
NSTimeZone *localTimeZone = [NSTimeZone systemTimeZone];
[df setTimeZone: localTimeZone];
NSLog(#"local time is %#" , [df stringFromDate: ds]);
return [df stringFromDate: d];
}