获取iPhone中两个特定时区之间的时差？

Question

例如，我想要亚洲/加尔各答时间与亚洲/迪拜之间的时差。

Answer 1

NSInteger differenceInSeconds = [timeZone1 secondsFromGMT] - [timeZone2 secondsFromGMT];

Note that this gives the current time difference between those timezones. If the two timezones observe daylight savings at different times of year, the time difference depends on when you evaluate this. If this matters to you, you should use secondsFromGMTForDate: to get the timezone offset at a specific date.

Answer 2

NSDate *now = [NSDate date];
NSDateFormatter *df = [[NSDateFormatter alloc] init] ;
[df setTimeStyle:NSDateFormatterFullStyle];
[df setTimeZone:[NSTimeZone timeZoneWithName:Str]];//str = timezone1(for you its kolkata)
[df setDateFormat:@"dd-MM-yyyy HH:mm"];
NSString *S1 = [df stringFromDate:now];
[df setDateFormat:@"dd-MM-yyyy HH:mm"];
NSDate *dd = [df dateFromString:S1];
//dd = date1 as per timezone
NSLog(@"dd > %@",dd);

[df release];


NSDate *dt = [NSDate date];
NSLog(@"dt = %@",dt);
NSDateFormatter *df1 = [[NSDateFormatter alloc] init];
[df1 setTimeStyle:NSDateFormatterFullStyle];
[df1 setTimeZone:[NSTimeZone timeZoneWithName:Str2]];//str2=timezone2(for you its dubai)
[df1 setDateFormat:@"dd-MM-yyyy HH:mm"];

NSString *S2 = [df1 stringFromDate:dt];

[df setDateFormat:@"dd-MM-yyyy HH:mm"];
NSDate *dd1 = [df dateFromString:S2];
//dd1 = date2 as per timezone
NSLog(@"dd1 > %@",dd1);


NSCalendar *sysCalendar = [NSCalendar currentCalendar];
unsigned int unitFlags = NSHourCalendarUnit | NSMinuteCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit;

NSDateComponents *conversionInfo = [sysCalendar components:unitFlags fromDate:dd  toDate:dd1  options:0];

NSLog(@"Conversion: %dmin %dhours %ddays %dmoths",[conversionInfo minute], [conversionInfo hour], [conversionInfo day], [conversionInfo month]);

i'm usin this code and its working properly.