Assets
The library uses the native SpriteKit texture atlases (SKTextureAtlas), and the opportunities for adding and editing sprite atlases in Xcode IDE.
Texture atlases of the Spine application itself are not used by the library. So you don't even have to worry about exporting them from there.
Also you can't use separate images located anywhere in the assets of your Xcode project. All images must be collected in sprite atlases. This is due to the optimizations that SpriteKit applies to texture atlases.
Apple devices have screens with different resolutions, so we usually have to prepare multiple versions of the same image:
Since Spine doesn't support multiple resolution images, just use basic version image as orange_bottle.png from the example above. Use version @2x or @3x will lead to the fact that the size of the character when you import in Xcode will be incorrect.
The Spine project always has a default skin named default that is created automatically. All images in the root of the Images folder must be added to the default atlas in the Xcode project later:
For each of the skin with the certain name, create a folder with an appropriate name and put all the images for this skin in it:
If you have several skins, you must spread out images on folders with the appropriate names. Images not related to any particular skins should be in the root of folder Images:
Technically it doesn't matter how you organize the images in the Spine project. Spine itself there are no restrictions for this. We just organize the images in such a way that they are easier to spread out into Xcode atlases, and we could have them properly loaded into SpriteKit.
Inside the asset catalog .xcassets create a new folder. In this folder further we will create sprite atlases for our character:
Choose a name for the folder that makes sense in the context of your project and is understandable to you. Later, we will need this name in the project code.
Inside the folder, create a new sprite atlas:
Add images to the atlas and additional versions of images for other resolutions:
By the way, you can add image versions for each platform if you need:
In the end, it should look something like this:
This is how the structure of the Images folder in the Spine project should look compared to the structure of atlases in the Xcode project:
You must enable the Provides Namespace option on the folder and all nested atlases in Xcode'a attribute inspector:
If you forget to enable this option, the library will simply not be able to upload images for your character