Unfortunately I don't think you can do that.
You can register your own custom scheme e.g yourFestival:// and pass data from the outside world (SMS , email , other apps) to your app.
Put a script on that page to redirect to your custom URL if is on iOS.
For example, here is a sample page which will take you to the Twitter app for a particular user or the Twitter website depending upon if you are on the web or on your iOS device:
iOS 9 supports Universal Links, which allows iOS to launch an app based on a standard http:// URL (based on the hostname) without the user having to go through Safari.
It requires some web server configuration (you need a website), but once setup, the registered app will open the link instead of Safari.
For the users that don't have iOS 9, you can use Smart Banners to ease the experience.
The question is old, but since I came across to this page now, years later, when searching for answer to the same question, I'll add answer on how to do it now:
Use Universal links. First enable "Associated Domains" on your App ID in developer.apple.com. Then add your domain as applink in Xcode (select Target->Signing & Capabilities->Associated Domains) and then create an apple-app-site-association file on your website.