判断 第二天 是否到来，

-(BOOL)nextDayIsComing

{

    NSUserDefaults *myDefault = [NSUserDefaultsstandardUserDefaults];

    NSDate *beforeDate = [myDefault objectForKey:@"date"];

    if (beforeDate == 0) {

        NSDateComponents *comp = [[NSDateComponentsalloc]init];

        [comp setMonth:07];

        [comp setDay:17];

        [comp setYear:2013];

        NSCalendar *myCal = [[NSCalendaralloc] initWithCalendarIdentifier:NSGregorianCalendar];

        NSDate *myDate = [myCal dateFromComponents:comp];

        beforeDate = myDate;

    }

    

    NSDate *now = [NSDate new];

    unsigned units  = NSMonthCalendarUnit|NSDayCalendarUnit|NSYearCalendarUnit;

    

    NSCalendar *myCal01 = [[NSCalendaralloc] initWithCalendarIdentifier:NSGregorianCalendar];

    NSDateComponents *secondComponent = [myCal01 components:units fromDate:now];

    NSInteger nowDay = [secondComponent day];

    

    NSDateComponents *firstComponent = [myCal01 components:units fromDate:beforeDate];

    NSInteger beforeDay = [firstComponent day];

    

    if (nowDay > beforeDay) {

        [myDefault setObject:now forKey:@"date"];

        return YES;

    }else{

        return YES;

    }

}