If we want to get the time intervals between the start time and end time then use the following code-

it will return the array of hours according to the start time and end time.

+ (NSMutableArray *)getTimeIntervals:(NSString *)startTime andEndTime:(NSString *)endTime {
    NSMutableArray *hoursArray=[[NSMutableArray alloc]init];
    NSDateFormatter *dateFormatter1=[[NSDateFormatter alloc]init];
    [dateFormatter1 setDateFormat:@"hh:mm a"];
    NSDate *startString = [dateFormatter1 dateFromString:startTime];
    NSDate *endString = [dateFormatter1 dateFromString:endTime];
    
    NSTimeInterval interval = [endString timeIntervalSinceDate:startString];
    NSInteger t1=(NSInteger)interval;
    NSInteger hours=t1/3600;
    

    for (int i=0;i<=hours; i++)
   {
        NSString *meridian;
        NSDate *plusOneHour ;
       if(i==0)
           plusOneHour=startString;

       else
           plusOneHour = [startString dateByAddingTimeInterval:60.0f * 60.0f];
       
        NSCalendar *calendar = [NSCalendar currentCalendar];
        NSDateComponents *components = [calendar components:(NSCalendarUnitHour | NSCalendarUnitMinute) fromDate:plusOneHour];
        NSInteger hour = [components hour];
        meridian=hour>=12?@"PM":@"AM";
        if(hour>12){
           hour=hour-12;
        }
       
        NSString *string = [NSString stringWithFormat:@"%ld %@", (long)hour,meridian];
        startString=plusOneHour;
        [hoursArray addObject:string];
    }

    
        return hoursArray;
}