从 weeks/weeks 年的天计算某些 NSDates

Question

有没有一种简单的方法可以根据 NSCalendar and/or NSCalendarComponents 的条件计算日期？我已经看了一段时间的文档，但它似乎有点复杂。例如，我需要接下来的 15 个偶数周 "Wednesday 6:00pm"s（包括这个，如果它是偶数并且还没有超过 date/time。）

Answer 1

这是一种方法，用于确定从哪个星期三开始，然后获取接下来的 14 个偶数周的星期三。这没有考虑你问题的时间部分，但你可以使用类似的方法来处理时间。

+ (NSArray *)nextFifteenEvenNumberedWeekWednesdays:(NSDate *)startingDate
{
    static const NSInteger Wednesday = 4;
    static const NSInteger OneDay = 60 * 60 * 24;
    NSCalendar *calender = [NSCalendar currentCalendar];
    NSDateComponents *startingDateComponents = [calender components:(NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitWeekday | NSCalendarUnitWeekOfYear)
                                                           fromDate:startingDate];

    // Go to the closest Wednesday
    NSInteger daysToWednesday = Wednesday - startingDateComponents.weekday;
    if (startingDateComponents.weekday > Wednesday) {
        // We already passed wednesday, so go to the next wednesday
        if (startingDateComponents.weekOfYear % 2 == 0) {
            // If this date is past Wednesday but is on an even week, then moving to the next wednesday
            // will be an odd week. So skip forward one week.
            startingDate = [startingDate dateByAddingTimeInterval:7 * OneDay];
        }
        daysToWednesday = 7 + daysToWednesday; // get the next Wednesday
    }
    startingDate = [startingDate dateByAddingTimeInterval:daysToWednesday * OneDay]; // Move to wednesday

    NSMutableArray *wednesdays = [NSMutableArray array];
    for (NSInteger i = 0; i < 15; i++) {
        // Add every other wednesday
        [wednesdays addObject:[startingDate dateByAddingTimeInterval:14 * i * OneDay]];
    }

    return [wednesdays copy];
}

Answer 2

我最后回答了我自己的问题。当您知道 -[NSCalendar dateBySettingUnit:value:ofDate:options:] 自动递增到下一个匹配日期时，这真的很容易。

NSCalendar *calendar = [NSCalendar calendarWithIdentifier:NSCalendarIdentifierISO8601];

NSDate *date = [NSDate date];

// find the next Wednesday 6 o'clock
date = [calendar dateBySettingUnit:NSCalendarUnitSecond value:0 ofDate:date options:0];
date = [calendar dateBySettingUnit:NSCalendarUnitMinute value:0 ofDate:date options:0];
date = [calendar dateBySettingUnit:NSCalendarUnitHour value:18 ofDate:date options:0];
date = [calendar dateBySettingUnit:NSCalendarUnitWeekday value:4 ofDate:date options:0];

// skip one week if it's not an even week
NSDateComponents *components = [calendar components:NSCalendarUnitWeekOfYear fromDate:date];
date = [calendar dateByAddingUnit:NSCalendarUnitWeekOfYear value:components.weekOfYear % 2 toDate:date options:0];

// 15 weeks of this
for (int i = 0; i < 15; i++)
{
    NSDate *testDate = [calendar dateByAddingUnit:NSCalendarUnitWeekOfYear value:i * 2 toDate:date options:0];
    NSLog(@"Date: %@", testDate);
}

从 weeks/weeks 年的天计算某些 NSDates

Calculating certain NSDates from days of weeks/weeks of years

ios

objective-c

time

nsdate

nscalendar