获取本月的第一天和最后一天

//MARK: - 获取本月的第一天和最后一天

• (NSString *)getMonthBeginWith:(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:NSCalendarUnitMonth 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];
  return beginString;
  }
• (NSString *)getMonthEndWith:(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:NSCalendarUnitMonth 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 *endString = [myDateFormatter stringFromDate:endDate];
  return endString;
  }