Similar to this question: How to make ios App Store link with parameters?
I am interested in passing parameters to the download link in the iOS app store. From what
You can pass a parameter to the app via Smart App Banner once the app is installed.
So I suggest providing one link to install the app, then a second link to a page with a Smart App Banner to pass the parameter.
This is a kluge, but it's the only way to do it in iOS. (iTunes store is a black box, whereas Play store passes Android params).