Get refferer in android very easy. But i can’t find how to do it in iOS…
As i know there is no such build-in functionality on iOS. But there are few services (paid) which offer it. Search for deferred deep linking or referral tracking.
Although, you can try to implement solution by yourself (i have tried such approach a year ago, and it works quite well, but failures in some circumstances): http://stackoverflow.com/a/22246314/1585840
There seems to be a way with “Marketing Campaign” unique URL links that I believe are passed in during app launch. You’ll likely need to write some ObjC/Swift code that then shares data with the c++ code (or you could use this only on the ObjC/Swift side doing the aggregation through NSURLSession).