win form input till array i annan klass C#

public partial class FormIngridients : Form
{
    Recipe m_recipe;            

    public FormIngridients(Recipe recipe)
    {
        InitializeComponent();
        m_recipe = recipe;                      
        if (string.IsNullOrEmpty(recipe.Name))
            this.Text = "No recipe name";           
        else
        {
            this.Text = recipe.Name + "Add ingridients";
        }
        InitializeGUI();
    }

    public Recipe Recipe
    {
        get { return m_recipe; }
        set
        {
            if (value != null)
                m_recipe = value;
        }
    }

    public void InitializeGUI()
    {
        if (m_recipe.Ingredients == null)
            m_recipe.Ingredients = new string[m_recipe.MaxNumOfIngredients];
        listIngredients.Items.Clear();                                          
        number.Text = m_recipe.CurrentNumOfIngredients.ToString();
    }

    public void UpdateGUI()
    {
        listIngredients.Items.Clear();
        int i;                                                          
        for (i = 0; i < m_recipe.MaxNumOfIngredients; i++)
            if (!string.IsNullOrEmpty(m_recipe.Ingredients[i]))
                listIngredients.Items.Add(m_recipe.Ingredients[i]);
        number.Text = m_recipe.GetCurrentNumberOfIngredients().ToString();
    }



    private void buttonAdd_Click(object sender, EventArgs e)
    {
        string ingredient = CheckInput();
        if( !string.IsNullOrEmpty(ingredient))
        {
            m_recipe.AddIngredient(ingredient);
            UpdateGUI();
        }
    }

    private string CheckInput()
    {
        string input = textIngridients.Text;
        if(string.IsNullOrEmpty(input))
        {
            MessageBox.Show("No ingredients!");
            return null;
        }
        return input;
    }

public class Recipe
{
    private string[] ingredientArray;
    private string name;
    private FoodCategory category;
    private string description;

    public Recipe(int maxNumOfIngredients)
    {
        ingredientArray = new string[maxNumOfIngredients];
        DefaultValues();
    }

    public string Description
    {
        get { return description; }
        set
        {
            if (!string.IsNullOrEmpty(value))
                    description = value;
        }
    }

    public string Name
    {
        get { return name; }
        set 
        {
            if (!string.IsNullOrEmpty(value))
                name = value;
        }
    }

    public FoodCategory Category
    {
        get { return category; }
        set
        {
            category = value;
        }
    }

    public int MaxNumOfIngredients
    {
        get { return ingredientArray.Length; }
    }

    public string[] Ingredients                      
    {
          get { return ingredientArray; }
         set
         {
            ingredientArray = value;
         }
    }

    public int FindVacantPosition()                             
    {
        for (int index = 0; index < ingredientArray.Length; index++)
        {
            if (ingredientArray[index] == null)
                return index;
        }
        return -1;
    }

    public bool CheckIndex(int index)
    {
        return (index >= 0) && (index < ingredientArray.Length);
    }

    public bool AddIngredient(string value)        
    {
        bool ok = true;
        int index = FindVacantPosition();
        if (index >= 0)
            ingredientArray[index] = value;
        else
            ok = false;

        return ok;
    }

    public int GetCurrentNumberOfIngredients()
    {
        int count = 0;
        int index;
        for (index = 0; index < ingredientArray.Length; index++)
        {
            if (!string.IsNullOrEmpty(ingredientArray[index]))
                count++;
        }
        return count;
    }

    public override string ToString()                               
    {
        string textOut = string.Format("{0,-20} {1,4} {2,-12}{3,-15}", name, CurrentNumOfIngredients, category.ToString(), descriptionText);
        return textOut;
    }