objective-c - 如何获得周末的日期？

Question

我想使用周末的日期在 NSLocalNotification 中使用它，但我不知道如何得到它，我试图用数学方法来做，但有时我得到的数字大于一个月中的天数。

Answer 1

请注意，iOS 支持多个日历，我不确定是否所有使用这些日历的文化都有周末的概念，并且它们是否总是意味着有两天。

您还需要处理一些事情：即使在使用公历的国家，一周也可能从星期一或星期日开始。

但是，如果我们假设周末相当于周六和周日，这可能对您有所帮助：

NSDate *referenceDate = [NSDate date];
NSDate *startOfThisWeek;
NSDate *saturday;

NSUInteger backupStartWeekday = [[NSCalendar currentCalendar] firstWeekday];
[[NSCalendar currentCalendar] setFirstWeekday:1]; // ensure week begins at sunday

[[NSCalendar currentCalendar] rangeOfUnit:NSWeekCalendarUnit
                                startDate:&startOfThisWeek
                                 interval:NULL
                                  forDate:referenceDate];

NSDateComponents *components = [[NSDateComponents alloc] init];
components.day = [[NSCalendar currentCalendar] maximumRangeOfUnit:NSWeekdayCalendarUnit].length; //the start of the next week

components.day = components.day - 2;
saturday = [[NSCalendar currentCalendar] dateByAddingComponents:components
                                                         toDate:startOfThisWeek
                                                        options:0];

[[NSCalendar currentCalendar] setFirstWeekday:backupStartWeekday];

Answer 2

关于获取日期的第一个问题可以解决为：

NSCalendar *calender=[NSCalendar currentCalendar];
NSRange daysRange=[calender rangeOfUnit:NSDayCalendarUnit inUnit:NSMonthCalendarUnit forDate:[NSDate date]];
NSUInteger numberOfDaysInMonth=daysRange.length;
//NSLog(@"num of days in current month : %ld",numberOfDaysInMonth);

NSDateComponents *dateComponents = [calender components:NSWeekdayCalendarUnit fromDate:[NSDate date]];
NSInteger dayCount=[dateComponents weekday];
//if today itself is saturday what you want to display? today or upcoming one... then do small changes here, for sat & sun.

NSInteger daysForSaturday=7-dayCount;

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"dd"];
NSUInteger todaysDate = [[formatter stringFromDate:[NSDate date]]integerValue];

// NSLog(@"Today is : %@",todaysDate);

NSUInteger comingSaturday=todaysDate+daysForSaturday;    
if (comingSaturday>numberOfDaysInMonth) {
    comingSaturday-=numberOfDaysInMonth;
}
NSUInteger comingSunday=comingSaturday+1;

NSLog(@"Coming.. Sat is : %ld, Sun in : %ld",comingSaturday, comingSunday);