Convert any timezone date in system timezone in iOS

问题

I am facing problem while converting given date into system time zone in iOS.

Source date: 2013-03-18 03:54:18 // its in AM format Destination date should be : 2013-03-18 03:30:15 //its in PM format.

How can I get this??

I have tried below code but getting wrong data and difference too.

NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";
NSLog(@"Post date::%@",postDate);
NSDate *utc = [fmt dateFromString:postDate];
fmt.timeZone = [NSTimeZone systemTimeZone];
NSString *local = [fmt stringFromDate:utc];
NSLog(@" local %@", local);

NSDate *date1 = [NSDate date];
NSString *currentDateString = [fmt stringFromDate:date1];
NSDate *currentDate = [fmt dateFromString:currentDateString];
NSUInteger flags = NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit;
NSDateComponents *difference = [[NSCalendar currentCalendar] components:flags fromDate:utc toDate:currentDate options:0];
NSLog(@"difference::%d",[difference day]);
NSLog(@"difference::%d",[difference hour]);
NSLog(@"difference::%d",[difference minute]);

EDIT: Outputs

Post date::2013-03-18 03:20:09 
local 2013-03-18 03:20:09 
difference::0 
difference::13 
difference::2

回答1:

NSString *openingHour = @"15:05:35 ";
 NSDateFormatter *workingHoursFormatter = [[NSDateFormatter alloc] init]; 
        NSTimeZone *timeZone = [NSTimeZone timeZoneWithName:@"UTC"];
        [workingHoursFormatter setTimeZone:timeZone];
        [workingHoursFormatter setDateFormat:@"HH:mm"];
        NSDate *openingTime = [workingHoursFormatter dateFromString:openingHour];

Can you try the above code it works for me , alter the date format to your need

回答2:

Replace your code from...

fmt.timeZone = [NSTimeZone systemTimeZone];

as like this

fmt.timeZone = [NSTimeZone localTimeZone];

This will works for you...

来源：https://stackoverflow.com/questions/15475348/convert-any-timezone-date-in-system-timezone-in-ios