Feature Request: Show warning during iOS build with missing .xcconfig

Did you verify this is a real problem by searching the NativeScript Forum and the other open issues in this repo?

Yes

Tell us about the problem

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Which platform(s) does your issue occur on?

iOS

Please provide the following version numbers that your issue occurs with:

• CLI: 4.2.0-2018-07-12-11970 (next)
  Project is using 4.1.0

Please tell us how to recreate the issue in as much detail as possible.

At some time in previous release, maybe NS 2 or 3x projects provided a build.xcconfig file which specifies:

ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
ASSETCATALOG_COMPILER_LAUNCHIMAGE_NAME = LaunchImage;

for the app icons during a build which works great. However, if this file is deleted (happened on a project today and took hours to figure out why the icons weren't showing when installing the app), then the app icon is not set during a build and no warnings/info is provided.

This could be a potential time saver for others in the future if the file is not found. I don't know all the implications of that file during xcode builds so I won't pretend to 😄 - it would have saved me several hours tracking down the file was deleted months ago from the project repository and that I had to set the icons in xcode on the build settings page after opening the workspace.

Commencez par localiser la gestion des builds iOS dans la CLI et recherchez les références à build.xcconfig ou aux paramètres ASSETCATALOG_COMPILER. Reproduisez un build avec le fichier manquant, déterminez ensuite où un avertissement devrait apparaître et vérifiez que l’avertissement s’affiche sans modifier les builds lorsque le fichier existe.