当系统日历是星期天时，NSCalendar 认为是新的一周

Question

当我的系统日历设置为星期天时，下面的代码认为这是新的一周，并整天显示下周。 例如 这周是第 39 周。 在 9 月 28 日星期日，我的代码认为这是新的一周，并显示下周（第 40 周）的所有天数，而不是我想要的第 39 周。 （我住的一周是从周一到周日而不是周日到周六）

NSDate *currentDate = [NSDate date];
NSCalendar *myCalendar = [NSCalendar currentCalendar];

[myCalendar setLocale:[NSLocale systemLocale]];

    NSDateComponents *currentComps = [myCalendar components:NSYearForWeekOfYearCalendarUnit |NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:currentDate];
int thisWeeksNumber = currentComps.weekOfYear;
NSLog(@"1  %d", thisWeeksNumber);

[myCalendar setFirstWeekday:2];


[currentComps setWeekday:2];
NSDate *firstDayOfTheWeek = [myCalendar dateFromComponents:currentComps];
[currentComps setWeekday:3];
NSDate *secondDayOfTheWeek = [myCalendar dateFromComponents:currentComps];
[currentComps setWeekday:4];
NSDate *thirdDayOfTheWeek = [myCalendar dateFromComponents:currentComps];
[currentComps setWeekday:5];
NSDate *fourthDayOfTheWeek = [myCalendar dateFromComponents:currentComps];
[currentComps setWeekday:6];
NSDate *fifthDayOfTheWeek = [myCalendar dateFromComponents:currentComps];
[currentComps setWeekday:7];
NSDate *sixthDayOfTheWeek = [myCalendar dateFromComponents:currentComps];
[currentComps setWeekday:1];
NSDate *seventhDayOfTheWeek = [myCalendar dateFromComponents:currentComps];


NSDateFormatter *myDateFormatter = [[NSDateFormatter alloc] init];
myDateFormatter.dateFormat = @"yyyy-MM-dd";
NSString *firstStr = [myDateFormatter stringFromDate:firstDayOfTheWeek];
NSString *secondStr = [myDateFormatter stringFromDate:secondDayOfTheWeek];
NSString *thirdStr = [myDateFormatter stringFromDate:thirdDayOfTheWeek];
NSString *fourthStr = [myDateFormatter stringFromDate:fourthDayOfTheWeek];
NSString *fifthStr = [myDateFormatter stringFromDate:fifthDayOfTheWeek];
NSString *sixthStr = [myDateFormatter stringFromDate:sixthDayOfTheWeek];
NSString *seventhStr = [myDateFormatter stringFromDate:seventhDayOfTheWeek];

NSLog(@"\n %@ \n %@ \n %@ \n %@ \n %@ \n %@ \n %@", firstStr, secondStr, thirdStr, fourthStr, fifthStr, sixthStr, seventhStr);

我的日志显示： 2014-09-21 22:40:36.040 NSCalendarProject[38667:90b] 2014-09-22 2014-09-23 2014-09-24 2014-09-25 2014-09-26 2014-09-27 2014-09-28

如您所见，我运行它的日期是 9 月 21 日星期日，它显示下一周的所有日子（如果我将日期设置为 9 月 28 日，则相同）

Answer 1

调用 [myCalendar setFirstWeekday:2] 只会将第一个工作日设置为星期一。但是，星期日仍然是“1”。因此，当 currentDate 是星期日时，“2”指的是该星期日之后的星期一，并且您的代码以下一周的日期结束。

您真正想要的是获得“currentDate”所在的一周的第一天。这段代码应该可以工作，但我不知道它是否是最优雅的解决方案。

NSCalendar *myCalendar = [NSCalendar currentCalendar];

    //create a 'sunday' date object for demonstration purposes
    NSDateComponents *sundayComponents = [[NSDateComponents alloc]init];
    sundayComponents.day = 28;
    sundayComponents.month = 9;
    sundayComponents.year = 2014;
    NSDate *sunday = [myCalendar dateFromComponents:sundayComponents];

    [myCalendar setLocale:[NSLocale systemLocale]];

    NSDateComponents *currentComps = [myCalendar components:NSYearForWeekOfYearCalendarUnit |NSYearCalendarUnit|NSMonthCalendarUnit|NSCalendarUnitWeekOfYear|NSWeekdayCalendarUnit fromDate:sunday];
    int thisWeeksNumber = currentComps.weekOfYear;
    NSLog(@"1  %d", thisWeeksNumber);

    [myCalendar setFirstWeekday:2];
    NSDate *beginningOfWeek = nil;
    [myCalendar rangeOfUnit:NSCalendarUnitWeekOfYear startDate:&beginningOfWeek
                   interval:NULL forDate: sunday];


    NSDateComponents *components = [[NSDateComponents alloc] init];

    NSDate *firstDayOfTheWeek = beginningOfWeek;
    components.day = 1;
    NSDate *secondDayOfTheWeek = [myCalendar dateByAddingComponents:components toDate:beginningOfWeek options:0];
    components.day = 2;
    NSDate *thirdDayOfTheWeek = [myCalendar dateByAddingComponents:components toDate:beginningOfWeek options:0];
    components.day = 3;
    NSDate *fourthDayOfTheWeek = [myCalendar dateByAddingComponents:components toDate:beginningOfWeek options:0];
    components.day = 4;
    NSDate *fifthDayOfTheWeek = [myCalendar dateByAddingComponents:components toDate:beginningOfWeek options:0];
    components.day = 5;
    NSDate *sixthDayOfTheWeek = [myCalendar dateByAddingComponents:components toDate:beginningOfWeek options:0];
    components.day = 6;
    NSDate *seventhDayOfTheWeek = [myCalendar dateByAddingComponents:components toDate:beginningOfWeek options:0];


    NSDateFormatter *myDateFormatter = [[NSDateFormatter alloc] init];
    myDateFormatter.dateFormat = @"yyyy-MM-dd";
    NSString *firstStr = [myDateFormatter stringFromDate:firstDayOfTheWeek];
    NSString *secondStr = [myDateFormatter stringFromDate:secondDayOfTheWeek];
    NSString *thirdStr = [myDateFormatter stringFromDate:thirdDayOfTheWeek];
    NSString *fourthStr = [myDateFormatter stringFromDate:fourthDayOfTheWeek];
    NSString *fifthStr = [myDateFormatter stringFromDate:fifthDayOfTheWeek];
    NSString *sixthStr = [myDateFormatter stringFromDate:sixthDayOfTheWeek];
    NSString *seventhStr = [myDateFormatter stringFromDate:seventhDayOfTheWeek];

    NSLog(@"\n %@ \n %@ \n %@ \n %@ \n %@ \n %@ \n %@", firstStr, secondStr, thirdStr, fourthStr, fifthStr, sixthStr, seventhStr);

    //log first day of week
    NSString *beginningWeek = [myDateFormatter stringFromDate:beginningOfWeek];
    NSLog(@"beginning of week is %@", beginningWeek);