Just a quick set of funcitons

RomanNumeralConversion.m

// Released under the terms of the LGPL 2.1

#import <Foundation/Foundation.h>

// Written with a little help from Copilot... this is a test of that functionality

// Create a function to convert a roman numeral to an integer
NSNumber *convertRomanToInt(NSString *string) {
    // Create a dictionary of roman numerals and their values
    NSDictionary *romanNumerals = @{
        @"I": @1,
        @"V": @5,
        @"X": @10,
        @"L": @50,
        @"C": @100,
        @"D": @500,
        @"M": @1000
    };
    
    // Create a variable to hold the value of the roman numeral
    NSNumber *value = [romanNumerals objectForKey:string];
    
    // If the value is nil, return nil
    if (value == nil) {
        return nil;
    }
    
    // Return the value
    return value;
}

NSNumber *convertRomanNumeralStringToNumber(NSString *string) {
    // Create a variable to hold the value of the roman numeral
    NSNumber *value = [NSNumber numberWithInt:0];
    
    // Create a variable to hold the previous value of the roman numeral
    NSNumber *previousValue = [NSNumber numberWithInt:0];
    
    // Loop through the string
    for (int i = 0; i < string.length; i++) {
        // Get the current character
        NSString *character = [string substringWithRange:NSMakeRange(i, 1)];
        
        // Get the value of the current character
        NSNumber *currentValue = convertRomanToInt(character);
        
        // If the current value is nil, return nil
        if (currentValue == nil) {
            return nil;
        }
        
        // If the current value is less than the previous value, subtract the current value from the total
        if ([currentValue intValue] < [previousValue intValue]) {
            value = [NSNumber numberWithInt:([value intValue] - [currentValue intValue])];
        }
        
        // Otherwise, add the current value to the total
        else {
            value = [NSNumber numberWithInt:([value intValue] + [currentValue intValue])];
        }
        
        // Set the previous value to the current value
        previousValue = currentValue;
    }
    
    // Return the value
    return value;
}

NSString *convertNumberToRomanNumeralString(NSNumber *n) {
    // Create a dictionary of roman numerals and their values
    NSDictionary *romanNumerals = @{
        @1: @"I",
        @5: @"V",
        @10: @"X",
        @50: @"L",
        @100: @"C",
        @500: @"D",
        @1000: @"M"
    };
    
    // Create a variable to hold the roman numeral string
    NSString *romanNumeralString = @"";
    
    // Create a variable to hold the current value
    NSNumber *currentValue = [NSNumber numberWithInt:0];
    
    // Create a variable to hold the previous value
    NSNumber *previousValue = [NSNumber numberWithInt:0];
    
    // Loop through the values
    for (int i = 0; i < [n intValue]; i++) {
        // Set the current value to the next value
        currentValue = [NSNumber numberWithInt:([currentValue intValue] + 1)];
        
        // If the current value is less than the previous value, subtract the current value from the total
        if ([currentValue intValue] < [previousValue intValue]) {
            currentValue = [NSNumber numberWithInt:([currentValue intValue] - [currentValue intValue])];
        }
        
        // Get the roman numeral for the current value
        NSString *romanNumeral = [romanNumerals objectForKey:currentValue];
        
        // Add the roman numeral to the roman numeral string
        romanNumeralString = [romanNumeralString stringByAppendingString:romanNumeral];
        
        // Set the previous value to the current value
        previousValue = currentValue;
    }
    
    // Return the roman numeral string
    return romanNumeralString;
}