How to avoid assigning the same GameObject individually for every prefab?

Question

In many times, prefabs that share the same script may require the same GameObject in the script. For example, in my game I want to make a series of card prefabs. Each card has their own image when shown, but has the same back image when hidden. My script for card is:

public class DraggingCard : DragAndDropItem
{
    public Sprite secretSprite; //This is the same for every card
    Sprite oringinalSprite; //This is individual for every card
    Image image;

    public void Awake()
    {
        image = GetComponent<Image>();
        oringinalSprite = image.sprite;
    }

    public void Activate()
    {
        image.sprite = oringinalSprite;
    }

    public void Hide()
    {
        image.sprite = secretSprite;
    }
}

But if I write this, I'll have to assign the secretSprite in the inspector for every DraggingCard prefab. I tried to set secretPrefab to be static or const but neither worked.

I believe there must be a clever way to avoid the repeat work. Could anyone tell me that? Thank you!

Answer 1

The easiest and cheapest method is to do it all in one go.

Select all of your prefabs in your project window (you can use search to get them all in one view, even if they're in different folders), and then assign the field once. The newly assigned value will be applied to every prefab in your selection.

Most scripts you write in Unity will support this type of multi-editing out of the box. If using a custom editor you might need to do a little work to enable this.

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Some alternatives you can use if you need something more elaborate:

A) In your Start script, load the texture you want with Resources.Load - you pass a path to the texture from a folder called Resources, which can be a static string. Just note that anything in a Resource folder will always be included in your build, even if you stop using it, and Unity won't be able to see this reference to pre-load the assets you need, so loading a lot of assets this way can introduce a performance hit.

B) Introduce an object with a "Manager" script into your scene, where the manager's job is to keep track of common references other scripts need. In Start, your other scripts can find the manager with built-in Find methods or a static GetInstance method, and ask it for their references. That way you only need to assign the references once to the manager object's prefab.

Answer 2

Assign the script and the secretSprite to your DraggingCard object before you make it a prefab. Then every DraggingCard instance that you place in your scene will already have the secretSprite assigned to it.