1. You Must Need knowledge (swift 4 or objective-c)
2. In order to modify the app you need to have knowledge in mobile technologies such as Xcode.
3. You also need to be able to install Xcode and its dependencies on your machine. We recommend you to use the Xcode official installation guide
3. You must have minimum Xcode Version 10.2.1
4. As I given in above features you get in source code. if you want add more features than it’s chargeable.
5. You must have knowledge of app store guidelines for upload an app.