Workaround a Bundle Bug

Bundle+Utils.swift

public extension Bundle {
	
	/**
	 Workaround a bug where the ``Bundle`` class is not aware of all of its bundles until it has encountered them.
	 
	 The case happens for instance when trying to load a storyboard from a reference in a storyboard that is in another module.
	 
	 First, an aside about module bundles.
	 A module bundle is named `<#modulename#>_<#targetname#>` and have the identifier `<#modulename#>-<#targetname#>-resources`.
	 The bundle folder name is the bundle name with the extension “`bundle`”.
	 
	 In your module `A`, in a storyboard, you thus define a reference to another storyboard in module `B`.
	 If none of the resources in `B` have been used when the storyboard `A` is loaded, the storyboard `B` won’t be found because the bundle of the module `B` won’t be found.
	 
	 This is probably a bug.
	 
	 To workaround it we do something very fragile but which seems to work:
	  we instantiate a `Bundle` for all of the bundles we can find in the resource path of the current bundle and
	  ask for the bundle identifier of all the bundles.
	 It seems `Bundle` keeps a cache of the bundle identifiers to bundle paths (unverified).
	 Asking the bundle identifiers is enough to update said cache and fix the aforementioned bug. */
	static func makeBundleAwareOfAllOtherBundlesInResources(of bundle: Bundle) {
		guard let rsrcURL = bundle.resourceURL, let files = try? FileManager.default.contentsOfDirectory(at: rsrcURL, includingPropertiesForKeys: nil) else {
			return
		}
		
		for bundleURL in (files.filter{ $0.pathExtension == "bundle" }) {
			/* This is fragile. It probably works because of a side-effect only. See this function doc for more info. */
			_ = Bundle(url: bundleURL)?.bundleIdentifier
		}
	}
	
}