如何将特定日期转换为 am/pm 格式？

Question

我从字符串中得到了一个特定的日期 NSString *str = @"2016-05-04 08:42:00 +0000"; 我想将其转换为 08:42 AM 格式。这是我的代码

NSString *str = @"2016-05-04 08:42:00 +0000";// put here item.TimeStart

NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init] ;
[dateFormatter1 setDateFormat:@"EEE, dd MMM YYYY HH:mm:ss VVVV"];// here give the format which you get in TimeStart

NSDate *date1 = [dateFormatter1 dateFromString: str];

dateFormatter1 = [[NSDateFormatter alloc] init] ;
[dateFormatter1 setDateFormat:@"hh:mm a"];

NSString *convertedString = [dateFormatter stringFromDate:date1];
NSLog(@"Converted String : %@",convertedString);

但这在转换后的字符串中返回 nil。为什么？？有什么想法吗？？

Answer 1

请添加以下行将时区时差设置为0，您将获得实际时间。

        //Add this line to set the time zone time difference to 0
        dateFormatter1.timeZone = [NSTimeZone timeZoneForSecondsFromGMT:0];

添加后，您的最终代码将如下所示：

    NSString *str = @"2016-05-04 08:42:00 +0000";

    NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init] ;
    [dateFormatter1 setDateFormat:@"YYYY-dd-MM HH:mm:ss VVVV"];

    NSDate *date1 = [dateFormatter1 dateFromString: str];

    dateFormatter1 = [[NSDateFormatter alloc] init];

    //Add this line to set the time zone time difference to 0
    dateFormatter1.timeZone = [NSTimeZone timeZoneForSecondsFromGMT:0];

    [dateFormatter1 setDateFormat:@"hh:mm a"];

    NSString *convertedString = [dateFormatter1 stringFromDate:date1];
    NSLog(@"Converted String : %@",convertedString);

Answer 2

它会帮助你

   -(NSDate *)calculateDate:(NSString *)getString
    {

        NSDateFormatter *Format = [[NSDateFormatter alloc] init];
        [Format setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss"];

        NSDate *aDate = [Format dateFromString:getString];

        if( !aDate )
        {
            [Format setDateFormat:@"yyyy-MM-dd'T'HH:mm:ss a"];
            [Format setLocale:[NSLocale localeWithLocaleIdentifier:@"en_US_POSIX"]];
            aDate = [Format dateFromString:getString];
        }

        return aDate;
    }

当我们有一个像2001-02-15T13:25:00这样的字符串，我们想把它格式化成12H格式，我们只需要定义local。

如何将特定日期转换为 am/pm 格式？

How to convert the particular date to the am/pm format?

objective-c

nsdateformatter