title: Detect if app has been downloaded from integrated app store IOS
body: <p>I am displaying on the touch of a button inside my app, an app on the appstore. The app pops up in a SKStoreProductViewController with the content of the app store. Now, is there any method to detect if the user has pressed install on the shown app, or even better, be alerted if the user has pressed intall and the app has finished installing? Since the user in my app in this way is capable of buying the fill version, I want to quit the trial when the download is over.</p>