使用NSCalendar来获取当前日期，年月日星期

最近有使用到日期获取，这里重新记一下算是复习

    NSCalendar  *calendar = [[NSCalendar  alloc]initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    NSDateComponents  *comps = [[NSDateComponents alloc] init];
    NSInteger unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitWeekday |
    NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
    NSDate *now=[NSDate date];
    comps = [calendar components:unitFlags fromDate:now];
    
    NSLog(@"weekday is %d",[comps weekday]);//注意：星期日是数字1，星期一时数字2，以此类推。。。
    NSLog(@"month is %d",[comps month]);
    NSLog(@"day is %d",[comps day]);
    NSLog(@"weekdayOrdinal is %d",[comps weekdayOrdinal]);