[英]Given a year and a week number, how do you get the date of the first day of the week?
我需要这个来获取每周图表中的数据。 这对我不起作用。 它返回的日期是所选年份的一月初。 有什么想法吗?
-(NSDate*) getFirstDateOfTheWeek:(NSString*) weekNr andYear: (NSString*) theYear {
int intYear = [theYear intValue];
int intWeek = [weekNr intValue];
NSCalendar *gregorian = [[NSCalendar alloc]
initWithCalendarIdentifier:NSGregorianCalendar];
[gregorian setLocale:[NSLocale currentLocale]];
NSDateComponents * comp = [[NSDateComponents alloc] init];
[comp setYear:intYear];
[comp setWeek:intWeek];
NSDate *dateOfFirstDay = [gregorian dateFromComponents:comp];
NSDateComponents *dateComponents =
[gregorian components:NSWeekdayCalendarUnit|NSWeekCalendarUnit|NSDayCalendarUnit|NSYearCalendarUnit|NSMonthCalendarUnit fromDate:dateOfFirstDay];
int year = [dateComponents year];
int month = [dateComponents month];
int day = [dateComponents day];
dateOfFirstDay= [gregorian dateFromComponents:dateComponents];
return dateOfFirstDay;
}
除了setYear和setWeek外,还应在NSDateComponents中设置setWeekday。
[comp setWeekday:intWeek];
然后,在获取新组件时,您不需要很多标志,因为您实际上只需要一天(其他时间用于调试):
[gregorian components:NSDayCalendarUnit|NSYearCalendarUnit|NSMonthCalendarUnit fromDate:dateOfFirstDay];
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