If the ffprophets:// link is opened on a device that doesn't have the app installed, the user will have a broken experience. You can work around this using a technique like the one described here: <a href="http://stackoverflow.com/questions/13044805/how-to-check-if-an-app-is-installed-from-a-web-page-on-an-iphone" rel="nofollow">http://stackoverflow.com/questions/13044805/how-to-check-if-...</a>