iOS 获取指定日期的时间（年、月、日、星期、时、分、秒等）

1、注意：weekday中1表示周日，2表示周一，7表示周六。

    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];        NSInteger unitFlags = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitWeekday | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;        NSDateComponents *comps = [calendar components:unitFlags fromDate:[NSDate date]];

NSLog(@"year = %ld, month = %ld, weekday = %ld, day = %ld, hour = %ld, minure = %ld, second = %ld",          comps.year,comps.month,comps.weekday,comps.day,comps.hour,comps.minute,comps.second);

如果还想获取其它时间信息，可以继续在  unitFlags 中添加类别（如：NSCalendarUnitTimeZone)