objective-c - 如何使用 Cocoa 查找任何给定日期的星期几

Question

我试图找出任何给定日期（即 2009 年 6 月 27 日）的哪一天（即星期一、星期五...）

谢谢你。

Answer 1

我一直在做：

NSDateFormatter* theDateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[theDateFormatter setFormatterBehavior:NSDateFormatterBehavior10_4];
[theDateFormatter setDateFormat:@"EEEE"];
NSString *weekDay =  [theDateFormatter stringFromDate:[NSDate date]];

这还有一个额外的好处是让您可以选择返回工作日的方式（通过更改 setDateFormat: 调用中的日期格式字符串

更多信息请访问：

http://developer.apple.com/documentation/Cocoa/Conceptual/DataFormatting/Articles/dfDateFormatting10_4.html#//apple_ref/doc/uid/TP40002369

Answer 2

你可以看看 NSDate 和 NSCalendar 类。例如，这里和这里

他们提供以下代码：

NSDate *today = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc]
                         initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *weekdayComponents =
                [gregorian components:(NSDayCalendarUnit | NSWeekdayCalendarUnit) fromDate:today];
NSInteger day = [weekdayComponents day];
NSInteger weekday = [weekdayComponents weekday];

Answer 3

使用 NSCalendar 和 NSDateComponents。如 NSDateComponents 文档中所示：

NSCalendar *gregorian = [[NSCalendar alloc]
initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *date = [gregorian dateFromComponents:comps];
NSDateComponents *weekdayComponents = [gregorian components:NSWeekdayCalendarUnit fromDate:date];
int weekday = [weekdayComponents weekday];

Answer 4

这就是我最终得到的结果，它完全符合预期。它需要一个日期，将日期更改为本月的第一天，并获取该日期的日期：

    NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:date];
NSDateComponents *monthDateComponents = [[NSCalendar currentCalendar] components: NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear |
                                         NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond fromDate: date];

//  build date as start of month
monthDateComponents.year = components.year;
monthDateComponents.month = components.month;
monthDateComponents.day = 1;

NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
//    [gregorian setFirstWeekday:1];

NSDate *builtDate =[gregorian dateFromComponents: monthDateComponents];
//    NSDateComponents *weekdayComponents =[gregorian components: NSCalendarUnitWeekday fromDate: builtDate];

NSDateFormatter *df = [NSDateFormatter new];
[df setDateFormat:@"E"];

NSString *firstDay = [df stringFromDate:builtDate];
if([firstDay isEqual:@"Sun"])  //  do for the other 6 days as appropriate
    return 7;