Mobile app developers use paid advertising campaigns to acquire new users. Based on the campaigns' performance, marketing managers decide where and how much to spend. Apple's new privacy mechanisms profoundly impact how performance marketing is measured. Starting iOS 14.5, all apps must get system permission for tracking explicitly via the new App Tracking Transparency Framework. Instead of relying on individual identifiers, Apple proposed a new performance mechanism called conversion value, an integer set by the apps for each user. The conversion value follows a set of rules and a schema that defines the integers based on the user's in-app behavior. The developers can get the number of installs per conversion value for each campaign. For conversion values to be helpful, we need a method that translates them to revenue. This paper investigates the task of attributing revenue to advertising campaigns using their reported conversion values. Our contributions are to formalize the problem, find the theoretically optimal revenue attribution function for any conversion value schema and show empirical results on past data of a free-to-play mobile game using different conversion value schemas.