Support easy loading of textures from an asset catalog

[JohnSundell]

Since Imagine Engine doesn't rely on the default system image loading mechanism (using UIImage(named:) on iOS) loading textures from an asset catalog is not super easy. While possible it requires you to create Animation or Texture instances using Image, like this:

let image = Image(named: "player")!
actor.animation = Animation(image: image)

It would be nicer if Imagine Engine could automatically search the app's asset catalog for an image with a given name, so that you could simply use:

actor.animation = Animation(textureNamed: "player")

[jussi80]

I can get down with this. 🙂

[jussi80]

Looks like we have run out of luck with this one: asset catalog is compiled as Assets.car file. That file is Apple's proprietary format which could be opened with CUICatalog, which is private class. If we use private class, it is very likely that apps with this will not be passed through AppStore review process. 🧐

[JohnSundell]

@jussi80 I don't think we should attempt to parse the asset catalogs ourselves. There's the NSDataAsset class which provides programmatic access to an asset catalog, it should be able to be used to access the data we need to load a texture 🙂

[jussi80]

@JohnSundell NSDataAsset seems to read everything else than image data which is rather strange. Taken from NSDataSet file

/// Data assets are not in the same class of stored content as images, so you cannot use a data asset to get image data for an image.

I added images and some random json filled files to .xcassets and images can't be opened, but those json files are no problem with the NSDataAsset. 🤔