Q:

How and where to create icons for iOS?

I've read the docs at AppIcons for iOS.
I read "Drag and drop your Assets.xcassets into Xcode (7.1 or newer version)." Not sure what that means exactly. Drop the folder on the Xcode icon?

A:

@dashman yep -exactly! Just drag'n'drop the folder in XCode. However, notice that this won't work directly from VSCode. So these are the actual steps:

Open in Finder Assets.xcassets folder located in app/App_Resources/ioS
select the folder and drag and drop in Xcode (opened or not)
the WYSIWIG screen for modifying your icons will load.

