在目标c中添加30分钟到当前时间

Question

我希望在目标c中添加30分钟4小时当前时间差异。

Ex：11.30 - 16.00

11.00 - 15.30 11.45至15.30

我该怎么做？

Answer 1

可以使用NSCalendar的{​​{3}}添加4小时30分钟，并且可以使用-dateByAddingComponents:toDate:options:进行舍入：

NSDate *now = [NSDate date];

// This assumes you want to use the Gregorian calendar.
NSCalendar *calendar = [NSCalendar calendarWithIdentifier:NSCalendarIdentifierGregorian];

// Add 4 hours and 30 minutes
NSDateComponents *fourAndAHalfHours = [NSDateComponents new];
fourAndAHalfHours.hour = 4;
fourAndAHalfHours.minute = 30;
NSDate *future = [calendar dateByAddingComponents:fourAndAHalfHours toDate:now options:NSCalendarMatchNextTimePreservingSmallerUnits];

// Now we want to round to next 30 minutes. If we're past the 30 minute mark, round to 0.
// Otherwise, round to 30.
NSInteger minutes = [calendar component:NSCalendarUnitMinute fromDate:future];
NSInteger roundTo = minutes >= 30 ? 0 : 30;

NSDate *rounded = [calendar nextDateAfterDate:future matchingUnit:NSCalendarUnitMinute value:roundTo options:NSCalendarMatchStrictly];

请注意，NSCalendarMatchStrictly此处将在夏令时更改后，为您提供更改后的下一个可用小时。如果您正在寻找不同的行为，请查看-nextDateAfterDate:matchingUnit:value:options:和NSCalendarMatchNextTimePreservingSmallerUnits。

Answer 2

试试这个：

 NSDate *dt = [NSDate date];
 NSCalendar *cal = [NSCalendar currentCalendar];
 NSDateComponents *comps = [cal components:NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond fromDate:dt];
 comps.hour = 4;
 if(comps.minute >= 30)
      comps.minute = -(comps.minute-30);
 else
      comps.minute = -comps.minute;
 comps.second = -comps.second;
 NSDate *newDate = [cal dateByAddingComponents:comps toDate:dt options:0];