RefTest2.cs

using Unity.Collections;
using Unity.Collections.LowLevel.Unsafe;
using UnityEngine;

public class RefTest2 : MonoBehaviour
{
    struct Data
    {
        public float value;
    }

    unsafe void Start()
    {
        NativeArray<Data> array = new NativeArray<Data>(10, Allocator.Temp);

        for(int i=0; i<10; i++)
            Do(ref UnsafeUtilityEx.ArrayElementAsRef<Data>(array.GetUnsafePtr(), i));

        foreach (var element in array)
        {
            Debug.LogFormat("{0:00.0}", element.value);
        }

        array.Dispose();
    }

    void Do(ref Data data)
    {
        data.value = Random.Range(0f, 10f);

    }
}