Firstly, Bitcode
is a total different concept which generates intermediate representation of a compiled program. This SO thread beautifully explains about it.
I believe you are looking for Slicing
. Per Apple Documentation:
Slicing is the process of creating and delivering variants of the app
bundle for different target devices. A variant contains only the
executable architecture and resources that are needed for the target
device. You continue to develop and upload full versions of your app
to iTunes Connect. The App Store will create and deliver different
variants based on the devices your app supports. Image resources are
sliced according to their resolution and device family. GPU resources
are sliced according to device capabilities. When the user installs an
app, a variant for the user’s device is downloaded and installed.
Trusting you are talking about Slicing
:
In Xcode, specify target devices and provide multiple resolutions of
images in the asset catalog.
So you should provide all target device images in asset catalog for slicing to work effectively.