iphone - 将 GMT 时间转换为本地时间

Question

我得到了当前的 GMT 时间 - 2013-05-15 08:55 AM

我当前的当地时间是 - 2013-05-15 02:06 PM ，时区是 - Asia/Kolkata

我尝试使用此代码将上述 GMT 转换为我的当地时间

   NSTimeZone* sourceTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"Asia/Kolkata"];
   [dateFormatter setTimeZone:sourceTimeZone];


      // timeStamp - is the above GMT time

   NSDate *dateFromString = [dateFormatter dateFromString:timeStamp];
    NSLog(@"local time is %@",dateFromString);

但这给了我错误的时间 - 2013-05-14 19:04:00 +0000 而不是2013-05-14 02:06 PM

为什么会发生这种情况？请帮我清除这个。在此先感谢

Answer 1

没有任何问题，NSDate实例永远不会有时区（它会，但它始终是 GMT，由+0000日期描述中的时区指示）。

您在代码中告诉 dateformatter 是您要解析的日期的时区是，Asia/Kolkata但您希望它是GMT.

首先，您需要NSDate根据输入日期字符串创建一个对象，并将时区设置为正确的时区，GMT如您所指示的。

NSTimeZone *gmtTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
[dateFormatter setTimeZone:sourceTimeZone];
NSDate *dateFromString = [dateFormatter dateFromString:timeStamp];
NSLog(@"Input date as GMT: %@",dateFromString);

然后，当您将日期显示为字符串时，请使用：

NSTimeZone* sourceTimeZone = [NSTimeZone timeZoneWithName:@"Asia/Kolkata"];
[dateFormatter setTimeZone:sourceTimeZone];
NSString *dateRepresentation = [dateFormatter stringFromDate:dateFromString];
NSLog(@"Date formated with local time zone: %@",dateRepresentation);

Answer 2

我发现将 GMT 时间转换为您当地时区的最短方法是

 NSDate* localDateTime = [NSDate dateWithTimeInterval:[[NSTimeZone systemTimeZone] secondsFromGMT] sinceDate:dateInGMT];

此外，将此日期值转换为字符串

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"HH:mm:ss"];//use the formatted as per your requirement. 

//Optionally for time zone converstions
[formatter setTimeZone:[NSTimeZone timeZoneWithName:@"..."]];

NSString *localTimeDateString = [formatter stringFromDate:localDateTime];

Answer 3

NSLog(@"local time is %@",[dateFormatter stringFromDate: dateFromString]);

Answer 4

NSTimeZone* gmtTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
NSTimeZone* localTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"Asia/Kolkata"];

NSDateFormatter *gmtDateFormatter = [[NSDateFormatter alloc] init];
[gmtDateFormatter setTimeZone:gmtTimeZone];

NSDate *date = [gmtDateFormatter dateFromString:timestamp];

NSDateFormatter *localDateFormatter = [[NSDateFormatter alloc] init];
[localDateFormatter setTimeZone:localTimeZone];

NSLog(@"local time is %@",[localDateFormatter stringFromDate:date]);

Answer 5

使用timeZoneWithName

NSDate *date=[[NSDate alloc]init];
NSDateFormatter *timeFormat = [[NSDateFormatter alloc] init];
[timeFormat setTimeZone:[NSTimeZone timeZoneWithName:@"Asia/Kolkata"]];
[timeFormat setDateFormat:@"HH:mm"];
NSString *dateStr=[timeFormat stringFromDate:date];