For our Android and iOS applications, we are using JsonServiceClient (for Android) and RestClient (for iOS). In both cases, we connect via HTTP and everything works correctly. If we wanted to use the HTTPS protocol, what would we need to change? Is it possible to use the same objects, or is it necessary to use other classes?
I don’t understand the question, why would you need to change your clients? Your server would need to use a CA-issued Certificate trusted by iOS/Android like LetsEncrypt. How you configure SSL on your deployed sever is up to you. We personally use a SSL terminated proxy like Kamal Proxy, prior to that we used the nginxproxy/acme-companion Docker container.