日期处理
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];NSDate *now;NSDateComponents *comps = [[NSDateComponents alloc] init];NSInteger unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSWeekdayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;now=[NSDate date];comps = [calendar components:unitFlags fromDate:now];week = [comps weekday]; month = [comps month];day = [comps day];hour = [comps hour];min = [comps minute];sec = [comps second];//Week:1 --星期天2--星期一3--星期二4--星期三5--星期四6--星期五7--星期六?