如何从年月日工作日乘以iOS中的某个整数的总和中提取日期分量？

Question

苹果示例项目DateSectionTitles演示了如何按年和月对部分进行分组，如何扩展它以支持年月日和工作日？

sectionIdentifier 是从持久日期属性 timestamp.

派生的瞬态属性

- (NSString *)sectionIdentifier {

    // Create and cache the section identifier on demand.

    [self willAccessValueForKey:@"sectionIdentifier"];
    NSString *tmp = [self primitiveSectionIdentifier];
    [self didAccessValueForKey:@"sectionIdentifier"];

    if (!tmp) {
        /*
         Sections are organized by month and year. Create the section identifier
         as a string representing the number (year * 1000 + month);
         this way they will be correctly ordered chronologically regardless of
         the actual name of the month.
         */
        NSCalendar *calendar = [NSCalendar currentCalendar];

        NSDateComponents *components = [calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit)
                               fromDate:[self timeStamp]];
        tmp = [NSString stringWithFormat:@"%d", [components year] * 1000 + [components month]];
        [self setPrimitiveSectionIdentifier:tmp];
    }
    return tmp;
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    id <NSFetchedResultsSectionInfo> theSection = [[self.fetchedResultsController sections] objectAtIndex:section];

    /*
     Section information derives from an event's sectionIdentifier, which is a string representing the number (year * 1000) + month.
     To display the section title, convert the year and month components to a string representation.
     */
    static NSDateFormatter *formatter = nil;

    if (!formatter)
    {
        formatter = [[NSDateFormatter alloc] init];
        [formatter setCalendar:[NSCalendar currentCalendar]];

        NSString *formatTemplate = [NSDateFormatter dateFormatFromTemplate:@"MMMM YYYY" options:0 locale:[NSLocale currentLocale]];
        [formatter setDateFormat:formatTemplate];
    }

    NSInteger numericSection = [[theSection name] integerValue];
    NSInteger year = numericSection / 1000;
    NSInteger month = numericSection - (year * 1000);

    NSDateComponents *dateComponents = [[NSDateComponents alloc] init];
    dateComponents.year = year;
    dateComponents.month = month;
    NSDate *date = [[NSCalendar currentCalendar] dateFromComponents:dateComponents];

    NSString *titleString = [formatter stringFromDate:date];

    return titleString;
}

我不知道像下面的代码那样计算年月日和工作日的确切算法。

tmp = [NSString stringWithFormat:@"%d", [components year] * 1000 + [components month]];

以及数据源方法的计算。

id <NSFetchedResultsSectionInfo> theSection = [[self.fetchedResultsController sections] objectAtIndex:section];

NSInteger numericSection = [[theSection name] integerValue];
NSInteger year = numericSection / 1000;
NSInteger month = numericSection - (year * 1000);

Answer 1

您需要一个 "algorithm" 来为每一天创建不同的结果（工作日与一天相同。没有 "Thursday, 13 March 2015"）。

假设您有 2015 年 3 月 13 日。一个好的唯一字符串是 20150313。或 year * 10000 + month * 100 + day。

例如：

NSDateComponents *components = [calendar components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay)
                                               fromDate:[self timeStamp]];
tmp = [NSString stringWithFormat:@"%d", [components year] * 10000 + [components month] * 100 + [components day]];

然后反转计算以取回各个组件：

NSInteger numericSection = [[theSection name] integerValue];
NSInteger year = numericSection / 10000;
NSInteger month = (numericSection - (year * 10000))/100;
NSInteger day = (numericSection - (year * 10000 + month * 100))

或者只是从以下部分的对象之一获取 NSDate：

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    id <NSFetchedResultsSectionInfo> theSection;// = [[self.fetchedResultsController sections] objectAtIndex:section];
    static NSDateFormatter *formatter = nil;

    if (!formatter)
    {
        formatter = [[NSDateFormatter alloc] init];
        [formatter setCalendar:[NSCalendar currentCalendar]];

        NSString *formatTemplate = [NSDateFormatter dateFormatFromTemplate:@"MMMM yyyy dd EEEE" options:0 locale:[NSLocale currentLocale]];
        [formatter setDateFormat:formatTemplate];
    }

    APLEvent *event = [[theSection objects] firstObject];
    if (event) {
        NSDate *date = [event timeStamp];
        return [formatter stringFromDate:date];
    }
    return nil;
}

如何从年月日工作日乘以iOS中的某个整数的总和中提取日期分量？

how to extract date components from sum of year month day weekday multiply by certain integer in iOS?

nsdate

nsdatecomponents

ios