Date Time Converion According to  TimeZone in iOS

Local timezone to other time zone:

//creating object of NSDateFormatter

NSDateFormatter *dateFormatter=[[NSDateFormatter alloc] init];

//setting format for date

[dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];

//setting timezone for dateFormatter

dateFormatter.timeZone=[NSTimeZone localTimeZone];

//getting localdate from system

NSString *localDate =[dateFormatter stringFromDate:[NSDate date]];

//Convert from string to date

NSDate *serverDate = [dateFormatter dateFromString:localDate];

//setting the dateformatter timezone according to which time needed

dateFormatter.timeZone=[[NSTimeZone alloc] initWithName:@"America/New_York"];

//getting date in desired formate

NSString *date =[dateFormatter stringFromDate:serverDate];

Other timezone to local time zone:

NSString *serverDateString=@"2014-06-19 10:50:10";

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];

dateFormatter.timeZone=[[NSTimeZone alloc] initWithName:@"America/New_York"];

dateFormatter.dateFormat=@"yyyy-MM-dd HH:mm:ss";

//Convert from string to date

NSDate *dateObject = [dateFormatter dateFromString:serverDateString];

//setting dateformatter to according to local timezone

dateFormatter.timeZone= [NSTimeZone localTimeZone];

//Now back from date to string

NSLog(@"From date to string: %@", [dateFormatter stringFromDate:dateObject]);

[dateFormatter setDateFormat:@"hh:mm a"];

NSString *time =[dateFormatter stringFromDate:dateObject];