Do web launch apps conform to Apple iOS App Store / Google Play App store Does some know, if apps, which immediately after launch opens a system browser window, conform to App Store / Play Store guidelines?

Or does an app need to show a screen and wait for users to take action?
There isn't an explicit rules in Apple's review guidelines for the App Store. 

But it seems to be that Apple would reject an app which would only open the navigator :


  Apple rejects applications that do not:
  
  have a user experience that feels like an "app" feel "at home" in the
  iOS ecosystem offer a differentiation from a mobile web experience


From : PhoneGap advice on dealing with Apple application rejections

So I would strongly suggest using an UIWebView.