Fix memory leak in IOS app

We have a newly developed app that is already published on App Store. Unfortunately it seems like the app is causing a memory leak. We are looking for a developer that can bug fix the app, and has access to IOS devices and has experience with IOS trackers such as Xcode Profiler etc.
The app has been coded in React Native as it is also running on Android. It would therefore also be good if the Android version could be monitered for similar issues.