Creating Asset Catalogs for an Application
Asset catalogs can be created using webMethods Mobile Development, or using platform-specific IDEs such as Xcode, or they can be created manually.
Note:
It is not mandatory for an asset catalog to define an image for all device/resolution combinations. The handset's operating system determines the nearest possible match according to the platform's guidelines.
You should create images that work with all devices at a given dpi, resolution, or scale. You are recommended to create handset-specific images only when there is a need to do so. This facilitates coding applications, reduces the number of assets to be created, and reduces the size of the final build.
You are not recommended to create asset catalogs manually for iOS.