I am trying to run the release build directly from the terminal and I did not found an option to do that.
From XCode what is required to do is:
Product -> Scheme -> Edit Scheme (cmd + <), make sure you're in the
Run tab from the side, and set the Build Configuration dropdown to
react-native run-ios -configuration Release
I did a PR to the React Native project to allow this feature. The PR can be check here: https://github.com/facebook/react-native/commit/ca7cbdee858e84c4a74a2d9c7be151f5cfdcfbfe
So, in the future, to run a release build from terminal you just only need to type the following command:
react-native run-ios --configuration Release