计算本周的第一天和最后一天

Question

参考预先回答的问题：Getting first and last days of current week

上面的链接有两个答案。其中一个是理论上的，另一个是一种称为 PyObjC（Python-Objective C 桥接语言）的语言，快速谷歌搜索确认 PyObjC 不适用于 iPhone SDK。

所以关于这个问题，如何将 PyObjC 代码翻译成与 iPhone SDK 兼容。

目标：假设今天（星期二）是 19 日，星期日。是 17 日（一周开始）和星期六。 23 日是周末。我想得到一个像 19/01 - 23/01 [即一周的开始（hypen）一周的结束]

Answer 1

如果您有一个NSDate，您可以使用当前的NSCalendar 来检索该日期的NSDateComponents。将NSDateComponents 的weekday 设置为1（一周的第一天），创建一个副本，并将副本的weekday 设置为7（一周的最后一天）。然后使用NSCalendar 将NSDateComponents 转换回各自的NSDate 对象，之后您可以使用NSDateFormatter 创建您的字符串表示。

此链接有一个关于如何获取日期工作日的示例：https://stackoverflow.com/questions/1057349#1057405

Answer 2

这里有一些代码，它还检查一个边缘情况，即一周的开始是在上个月开始的：

// Finds the date for the first day of the week
- (NSDate *)getFirstDayOfTheWeekFromDate:(NSDate *)givenDate
{
    NSCalendar *calendar = [NSCalendar currentCalendar];

    // Edge case where beginning of week starts in the prior month
    NSDateComponents *edgeCase = [[NSDateComponents alloc] init];
    [edgeCase setMonth:2];
    [edgeCase setDay:1];
    [edgeCase setYear:2013];
    NSDate *edgeCaseDate = [calendar dateFromComponents:edgeCase];

    NSDateComponents *components = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:edgeCaseDate];
    [components setWeekday:1]; // 1 == Sunday, 7 == Saturday
    [components setWeek:[components week]];

    NSLog(@"Edge case date is %@ and beginning of that week is %@", edgeCaseDate , [calendar dateFromComponents:components]);

    // Find Sunday for the given date
    components = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:givenDate];
    [components setWeekday:1]; // 1 == Sunday, 7 == Saturday
    [components setWeek:[components week]];

    NSLog(@"Original date is %@ and beginning of week is %@", givenDate , [calendar dateFromComponents:components]);

    return [calendar dateFromComponents:components];
}

编辑：上面的相关代码

- (NSDate *)firstDayOfWeekFrom:(NSDate *)givenDate {
  NSCalendar *calendar = [NSCalendar currentCalendar];

  NSDateComponents *components = [calendar components:NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayCalendarUnit fromDate:givenDate];
  [components setWeekday:1]; // 1 == Sunday, 7 == Saturday
  [components setWeekOfYear:[components weekOfYear]];

  return [calendar dateFromComponents:components];
}

Answer 3

这是我几天前一直在寻找的东西，终于找到了。 NSDate 中有一个方法 rangeOfUnit:startDate:interval:forDate: 并以简单的方式执行此操作。您可以在以下位置查看详细信息： Current Week Start and End Date

Answer 4

NSDate *weekDate = [NSDate date];
NSCalendar *myCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

NSDateComponents *currentComps = [myCalendar components:( NSYearCalendarUnit | NSMonthCalendarUnit | NSWeekOfYearCalendarUnit | NSWeekdayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit) fromDate:weekDate];
int ff = currentComps.weekOfYear;
NSLog(@"1  %d", ff);

[currentComps setWeekday:1]; // 1: sunday
NSDate *firstDayOfTheWeek = [myCalendar dateFromComponents:currentComps];
[currentComps setWeekday:7]; // 7: saturday
NSDate *lastDayOfTheWeek = [myCalendar dateFromComponents:currentComps];

NSDateFormatter *myDateFormatter = [[NSDateFormatter alloc] init];
myDateFormatter.dateFormat = @"dd EEEE";
NSString *firstStr = [myDateFormatter stringFromDate:firstDayOfTheWeek];
NSString *secondStr = [myDateFormatter stringFromDate:lastDayOfTheWeek];

NSLog(@"first - %@ \nlast - %@", firstStr, secondStr);