Manifest files/app thinning
App thinning (https://developer.apple.com/library/content/documentation/IDEs/Conceptual/AppDistributionGuide/AppThinning/AppThinning.html) is a feature that was added back in iOS 9 as a way of optimizing the installation of iOS apps on the user's device, "by tailoring app delivery to the capabilities of the user's particular device, with minimal footprint" (Source: Apple). That is, developers can distribute apps that will result in faster downloads and leave more space available on the end user's devices.
App thinning automatically detects the device type and downloads only the relevant content for that device, at the correct resolution, from the resource catalog.
Slicing is an aspect of app thinning which delivers a different version of the app bundle for different target devices, as opposed to encompassing all the types of target devices within the one ipa. By slicing the file via iTunes Connect, the user will get the image resources according to their device...
