gistfile1.m

-(NSInteger)length
{
    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
    NSDateComponents *components = [calendar components:NSDayCalendarUnit
                                               fromDate:self.dateFrom
                                                 toDate:self.dateTo
                                                options:0];
    
   double days = (double)components.day;
    
    //  handle edge cases
    if(timeOfDayFrom.time == TimeOfDayMorning && timeOfDayTo.time == TimeOfDayEvening)
        days += 0.5f;
    if(timeOfDayFrom.time == TimeOfDayEvening && timeOfDayTo.time == TimeOfDayMorning)
        days -= 0.5f;
    
    NSInteger total = round(days);
    
    return (total >= 1) ? total : 1;
}