Thinger.io supports TLS both in cloud and local deployments. For local deployments it is required to install the SSL certificate according to your domain, as any other web solution. Moreover, the API endpoints can eve be consumed over non-secure connections, so I cannot see any technical problem for releasing an APP to the iOS store. Just note that the SSL certificates are not bundled with the APP, it is something configured in the server and validated by the application (using the device trusted certificates store). Other thing is that you want to use Thinger.io over HTTPS using self-signed certificates, which is not feasible for a real deployment. In this case it is better to use LetsEncrypt.