How to save an int array to a JSON file for saving and loading

I currently have the following code and I would like to save the int levelsComplete to a JSON file and also be able to retrieve it. I have looked at lots of tutorials and tried following them but none of them seem to work for my case.

public Button[] levels;
    public int[] levelsComplete;

    // Start is called before the first frame update
    void Start()
    {
        levelsComplete[0] = 1;
    }

    // Update is called once per frame
    void Update()
    {
 
        for (int i = 0; i <= 21; i++)
        {
            if (levelsComplete[i] == 1)
            {
                levels[i].interactable = true;
            } else
            {
                levels[i].interactable = false;
            }
        }
    }

Then anything we type in this box won’t be much use either I suppose!!

But here we go anyway…

Load/Save steps:

An excellent discussion of loading/saving in Unity3D by Xarbrough:

And another excellent set of notes and considerations by karliss_coldwild:

Loading/Saving ScriptableObjects by a proxy identifier such as name:

When loading, you can never re-create a MonoBehaviour or ScriptableObject instance directly from JSON. Save data needs to be all entirely plain C# data with no Unity objects in it.

The reason is they are hybrid C# and native engine objects, and when the JSON package calls [ICODE]new[/ICODE] to make one, it cannot make the native engine portion of the object, so you end up with a defective “dead” Unity object.

Instead you must first create the MonoBehaviour using AddComponent() on a GameObject instance, or use ScriptableObject.CreateInstance() to make your SO, then use the appropriate JSON “populate object” call to fill in its public fields.

If you want to use PlayerPrefs to save your game, it’s always better to use a JSON-based wrapper such as this one I forked from a fellow named Brett M Johnson on github:

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Thank you so much for your help!