function cleanLaunchStoryboardImages (projectRoot, projectConfig, locations) {
    const splashScreens = projectConfig.getSplashScreens('ios');
    const platformProjDir = path.relative(projectRoot, locations.xcodeCordovaProj);
    const launchStoryboardImagesDir = getLaunchStoryboardImagesDir(projectRoot, platformProjDir);
    if (launchStoryboardImagesDir) {
        const resourceMap = mapLaunchStoryboardResources(splashScreens, launchStoryboardImagesDir);
        const contentsJSON = getLaunchStoryboardContentsJSON(splashScreens, launchStoryboardImagesDir);

        Object.keys(resourceMap).forEach(targetPath => {
            resourceMap[targetPath] = null;
        });
        events.emit('verbose', `Cleaning storyboard image set at ${launchStoryboardImagesDir}`);

        // Source paths are removed from the map, so updatePaths() will delete the target files.
        FileUpdater.updatePaths(
            resourceMap, { rootDir: projectRoot, all: true }, logFileOp);

        // delete filename from contents.json
        contentsJSON.images.forEach(image => {
            image.filename = undefined;
        });

        events.emit('verbose', 'Updating Storyboard image set contents.json');
        fs.writeFileSync(path.join(projectRoot, launchStoryboardImagesDir, 'Contents.json'),
            JSON.stringify(contentsJSON, null, 2));
    }
}
Removes the images from the launch storyboard's image set and updates the image set's contents.json
file appropriately.

@param  {string} projectRoot        Path to the project root
@param  {Object} projectConfig      The project's config.xml
@param  {Object} locations          A dictionary containing useful location paths