Is .xcassets resource only for app icons and launch images or for our own image assets also? I do know that we can add our images to the .xcassets file, but is it good practice to do so?
Use of xcassets is the new standard as of Xcode 5 and iOS 7. Import images by clicking on the blue folder called "Images.xcassets" then click on the small "+" plus sign at the bottom of the window that appears. Now choose "Import" to put images in there.
This is also the new location of the icon and launch images instead of the standard target->general location, although this is where you still have the option to not choose "Don't use asset catalogs".
It's really helpful because you'll only see 1 image name instead of duplicate names with extensions like "@2x" and "-568h@2x".
Apple said that the asset catalog editor in Xcode manages your app’s images, grouping together various resolutions of the same asset. When building, Xcode compiles the asset catalog into the most efficient bundle for final distribution.
So basic asset catalog can manage AppIcon and LaunchImage.
But you can also add new images to new folders as below.
late to the party but yes it is the best practice
and also There is one tool : AVXCassets Generator with which you can directly generate XCAssets file for all your icons and images just by one click.
来源：https://stackoverflow.com/questions/19441935/use-of-xcassets