比较两个日期的大小 NSDate获取当前日期 进行比较

取得当前的年月日，当前的时分秒获得，周几和星期几获得

NSDate*date = [NSDate date];

NSCalendar*calendar = [NSCalendar currentCalendar];

NSDateComponents*comps;

 

// 年月日获得

comps =[calendar components:(NSYearCalendarUnit | NSMonthCalendarUnit |NSDayCalendarUnit)

                                      fromDate:date];

NSIntegeryear = [comps year];

NSIntegermonth = [comps month];

NSIntegerday = [comps day];

NSLog(@"year:%d month: %d, day: %d", year, month, day);

 

//当前的时分秒获得

comps =[calendar components:(NSHourCalendarUnit | NSMinuteCalendarUnit |NSSecondCalendarUnit)

                                      fromDate:date];

NSIntegerhour = [comps hour];

NSIntegerminute = [comps minute];

NSIntegersecond = [comps second];

NSLog(@"hour:%d minute: %d second: %d", hour, minute, second);

 

// 周几和星期几获得

comps =[calendar components:(NSWeekCalendarUnit | NSWeekdayCalendarUnit |NSWeekdayOrdinalCalendarUnit)

                                      fromDate:date];

NSInteger week = [comps week]; // 今年的第几周

NSIntegerweekday = [comps weekday]; // 星期几（注意，周日是“1”，周一是“2”。。。。）

NSIntegerweekdayOrdinal = [comps weekdayOrdinal]; // 这个月的第几周

NSLog(@"week:%d weekday: %d weekday ordinal: %d", week, weekday, weekdayOrdinal);

 

NSDateFormatter*dateFormatter = [[NSDateFormatter alloc]init];

       if(dateSwitch.on)

       [dateFormattersetDateFormat:@"dd-MMM-yyy,hh:mm:ss"];

       else

       [dateFormatter setDateFormat:@"hh:mm:ss"];

       labelTime.text = [dateFormatter stringFromDate:[NSDatedate]];

       labelTime.font = [UIFontsystemFontOfSize:fontSlider.value];

       [dateFormatter release];

注意：[calendar components:(NSWeekCalendarUnit | NSWeekdayCalendarUnit |NSWeekdayOrdinalCalendarUnit)  标志位，不能一次设置太多，不好用，我也不知道为什么，有待考证~