Multiple sprite loading in Unity3d

This days I was blocked with a extremely simple task. I wasn’t able to load a multiple sprite in Unity using Resources.Load. Surprisingly there was few or unclear information in the subject so I share a simple solution.

Short solution

    Dictionary<string, Sprite> LoadSpriteSheet(string path) {
        Dictionary<string, Sprite> spriteSheet = new Dictionary<string, Sprite>();
        Sprite[] sprites = Resources.LoadAll<Sprite>(path);
        foreach (Sprite sprite in sprites) {
            spriteSheet.Add(sprite.name, sprite);
        }
        return spriteSheet;
    }

Explained example

I have a sprite called “deck” in the path “Resources/Sprites/” with the sprite mode set to “Multiple” and I used the sprite editor to generate the subsprites for each card.

As code example I made a MonoBehaviour that shows a random card when you press the key “R”. Tested on Unity 5.5.0 and should work fine on Unity 5.x:

using System.Collections.Generic;
using UnityEngine;

// be safe... with this you're sure you have an SprteRenderer in the GameObject
[RequireComponent(typeof(SpriteRenderer))]

public class ShowRandomCard : MonoBehaviour {

    SpriteRenderer spriteRenderer;
    Dictionary<string, Sprite> deck;

    Dictionary<string, Sprite> LoadSpriteSheet(string path) {
        // a hash container to store the "subsprites"
        Dictionary<string, Sprite> spriteSheet = new Dictionary<string, Sprite>();

        // IMPORTANT: use LoadAll instead Load for "multiple" sprite's type
        // gets all subsprites in an array
        Sprite[] sprites = Resources.LoadAll<Sprite>(path);

        foreach (Sprite sprite in sprites) {
            // iterate the array and store it in the hash
            spriteSheet.Add(sprite.name, sprite);
        }

        return spriteSheet;
    }

    void Awake () {
        // get the reference of the GameObject's SpriteRenderer
        spriteRenderer = GetComponent<SpriteRenderer>();

        // load the deck calling our custom made function
        deck = LoadSpriteSheet("Sprites/deck");
    }

    void Update () {
        if (Input.GetKeyDown("r")) {
            // this generates a string like "1A" meaning rank 1 suite A
            string cardName = $"{Random.Range(0, 12) + 1}{(char)('A' + Random.Range(0, 4))}";

            // get the sprite by name and set the SpriteRenderer with it
            spriteRenderer.sprite = deck[cardName];
        }
    }
}

Expanding your toolset

For all simple and time saving functions like LoadSpriteSheet I never use singletons. They are just simple and independent funtions. Functions, not classes! So the way I organize to access them project wide is using static classes which are like C++ namespaces on steroids.

// Utils.cs example
// ...

public static class Utils {
    // ...

    public static Dictionary<string, Sprite> LoadSpriteSheet(string path) {
        // ...
    }
}

// SomeBehaviour.cs example

void Awake() {
    Utils.LoadSpriteSheet("deck");
}

Conclusion

Be happy and creative with your beautiful sprite sheets in Unity3d!