Question

可能重复：
Getting date from [NSDate date] off by a few hours

我想用实际日期计算实际当天的午夜时间，这里是代码：

NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
    [formatter setDateFormat:@"dd/MM/yyyy"];
 NSDate *today = [NSDate date];
    NSString *todayStr = [NSString stringWithFormat:@"%@ 12:59 PM",[formatter stringFromDate:today]];
NSLog(@"%@",todayStr);
[formatter setDateFormat:@"dd/MM/yyyy hh:mm a"];
NSDate *midNight = [formatter dateFromString:todayStr];
NSLog(@"%@",midNight);

但我得到的日志是：

23/01/2013 12:59 PM
2013-01-23 10:59:00 +0000

为什么midNight不是实际的午夜，为什么它与formatter的格式不同？

Answer 1

这会计算当地时区的午夜时间。

NSDate *d = [NSDate date];
NSCalendar *cal = [NSCalendar currentCalendar];
NSDateComponents *comps = [cal components:NSEraCalendarUnit|NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit fromDate:d];
d = [cal dateFromComponents:comps];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"dd/MM/yyyy hh:mm a"];
NSString *dateStr = [formatter stringFromDate:d];
NSLog(@"%@", dateStr);

打印23/01/2013 12:00 AM

计算实际日期的午夜日期

1 个答案: