objective-c - 在 iOS SDK 中获取周数

Question

我想从日期获取一年中的周数。我尝试了如下代码，但给了我错误的周数。

我的周数代码：

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"YYYY-MM-dd"];
    NSDate *date = [dateFormatter dateFromString:@"2012-09-15"];


    NSCalendar *calendar = [NSCalendar currentCalendar];

    NSLog(@"week: %i", [[calendar components: NSWeekOfYearCalendarUnit fromDate:date] weekOfYear]); //Display 38 instead of 37
}

注意：如果我尝试使用[NSDate date]显示正确的。

帮我解决这个问题..谢谢，

Answer 1

目标C：

 NSCalendar *calendar = [NSCalendar currentCalendar];
 NSDateComponents *dateComponent = [calendar components:(NSWeekOfYearCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit) fromDate:[NSDate date]];
 NSLog(@"%@",dateComponent);

更新

 NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *dateComponent = [calendar components:(NSCalendarUnitWeekOfYear | NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear) fromDate:date];
    NSLog(@"%@",dateComponent);

迅速：

let calendar = NSCalendar.currentCalendar()
let dateComponent = calendar.components([.WeekOfYear, .Day, .Month, .Year], fromDate: NSDate(timeIntervalSinceNow: 0))
print("weekOfYear \(dateComponent.weekOfYear)")

斯威夫特 3 - 斯威夫特 5：

let component = Calendar.current.component(.weekOfYear, from: Date())
print("Week of Year \(component)")

Answer 2

[NSCalendar currentCalendar]默认为您提供公历。您可以使用

NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSISO8601Calendar];

获取符合 ISO 08601 的日历，该日历的日期为第37周。

Answer 3

Swift 3：您需要知道Date所选月份的最后一个。比检查本周的周数，这将是您每月的周数

return Calendar.current.component(.weekOfMonth, from: lastDate ?? Date())

Answer 4

ObjectiveC 中的更新代码使用了 Xcode 版本 - 9.1 - ：

    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *dateComponent = [calendar components:(NSCalendarUnitWeekOfYear | NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear) fromDate:[NSDate date]];
    NSLog(@"%ld",(long)[dateComponent weekOfYear]);