iPhone SDK，如何获取NSDATE的对象，即将来临的20:00？

Question

有人知道如何获得即将到来的星期五20:00的NSDATE吗？

Answer 1

是的， 本文 教您如何获得当前周的星期日。

我很快将其改编成20:00星期五（假设Gregorian日历）

NSDate *today = [[NSDate alloc] init];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

// Get the weekday component of the current date
NSDateComponents *weekdayComponents = [gregorian components:NSWeekdayCalendarUnit fromDate:today];

/*
Create a date components to represent the number of days to add to the current date.
The weekday value for Friday in the Gregorian calendar is 6, so add the difference between 6 and today to get the number of days to add.
Actually, on Saturday that will give you -1, so you want to subtract from 13 then take modulo 7
*/
NSDateComponents *componentsToAdd = [[NSDateComponents alloc] init];
[componentsToAdd setDay: (13 - [weekdayComponents weekday]) % 7];

NSDate *friday = [gregorian dateByAddingComponents:componentsToAdd toDate:today options:0];

/*
friday now has the same hour, minute, and second as the original date (today).
To normalize to midnight, extract the year, month, and day components and create a new date from those components.
*/
NSDateComponents *components =
    [gregorian components:(NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit)
               fromDate: friday];

// And to set the time to 20:00
[components setHour:22];

friday = [gregorian dateFromComponents:components];