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I've simply been following the documentation found here: Creating a Widget Extension. However, for some reason when I try to launch the extension I'm faced with the error: WatchWidget does not define either an NSExtensionMainStoryboard or NSExtensionPrincipalClass key with a string value in the NSExtension dictionary in its Info.plist Which is indeed correct, however I'm uncertain what it's supposed to point to? I currently just have the WidgetFile, assets and the info.plist :)