如何在foreach中隐式转换自定义IEnumerable？

using System;
using System.Collections;

public class MyCollection : IEnumerable
{
    private int[] data;

    public MyCollection(int[] values)
    {
        data = values;
    }

    public IEnumerator GetEnumerator()
    {
        return new MyEnumerator(data);
    }
}

public class MyEnumerator : IEnumerator
{
    private int[] data;
    private int position = -1;

    public MyEnumerator(int[] values)
    {
        data = values;
    }

    public object Current
    {
        get
        {
            return data[position];
        }
    }

    public bool MoveNext()
    {
        position++;
        return (position < data.Length);
    }

    public void Reset()
    {
        position = -1;
    }
}

public class Program
{
    public static void Main()
    {
        int[] values = { 1, 2, 3, 4, 5 };
        MyCollection collection = new MyCollection(values);

        foreach (int value in collection)
        {
            Console.WriteLine(value);
        }
    }
}