Load Testing a native IOS application during offline mode

Hi All, I work for a healthcare client, Our client is Implementing a new architecture for the mobile application. they are developing a native mobile application to work in the offline mode (Like Entering the patient details) using a realm db(which is located in the mobile itself), and later when we go to online the data from the realm db goes to ROS(Real object server) which will be located in the server.

Here we are planning to test the app both in online and offline modes but we are unable to figure out how to test the app in offline mode as the app sits in mobile along with the Realm DB. Please let me know if anyone has done this kind of testing before or know how to test in offline mode by using the Loadrunner tool.