You should create a texture atlas and use SKTextureAtlas
methods:
– preloadWithCompletionHandler:
+ preloadTextureAtlases:withCompletionHandler:
Here is what documentation says about this:
Sprite Kit creates a background task that loads the texture data from the atlas. Then, Sprite Kit returns control to your game. After the texture atlas is loaded, your completion handler is called.
If you need to preload multiple texture atlases at once, use the
preloadTextureAtlases:withCompletionHandler:
method instead.