Say I want a bundled image to take up all available screen width in an iPhone app - for example a banner. I\'d create my_banner.png with width 320px
I raised the same question to apple technical support and they confirm that for fullscreen image it can't be done in asset catalog: "Currently, there is no way for the Asset Catalog to load device specific images. If your app needs to support device specific images you will need to implement your own code to detect the screen size and choose the appropriate image. You can file an enhancement request by using the following link. Be sure to explain your use case for this feature. "