iOS-一周第一天和最后一天

• (NSString *)getMonthBeginAndEndWith:(NSString *)dateStr {

  NSDateFormatter *format = [[NSDateFormatter alloc] init];
  [format setDateFormat:@"yyyy-MM"];
  NSDate *newDate = [format dateFromString:dateStr];
  double interval = 0;
  NSDate *beginDate = nil;
  NSDate *endDate = nil;
  NSCalendar *calendar = [NSCalendar currentCalendar];

  [calendar setFirstWeekday:2]; //设定周一为周首日
  BOOL ok = [calendar rangeOfUnit:NSMonthCalendarUnit
  startDate:&beginDate
  interval:&interval
  forDate:newDate];
  //分别修改为 NSDayCalendarUnit NSWeekCalendarUnit NSYearCalendarUnit
  if (ok) {
  endDate = [beginDate dateByAddingTimeInterval:interval - 1];
  } else {
  return @"";
  }
  NSDateFormatter *myDateFormatter = [[NSDateFormatter alloc] init];
  [myDateFormatter setDateFormat:@"YYYY.MM.dd"];
  NSString *beginString = [myDateFormatter stringFromDate:beginDate];
  NSString *endString = [myDateFormatter stringFromDate:endDate];
  NSString *s = [NSString stringWithFormat:@"%@-%@", beginString, endString];
  return s;
  }