Able to launch Expo app on iOS simulator after detaching?

I’m trying to support running our app in the Expo app on the iOS simulator even though our app is detached, as we’re only detaching for a few specific features and 99% of the development cycle doesn’t require detaching.

If I run exp start --ios after detaching, exp tries to launch my app using the URI scheme specified in app.json. This means it either tries to launch by detached debug build, or if that’s not installed, the launching fails entirely. Additionally, if the Expo app is not installed on the simulator, it is not automatically installed. If the Expo app is already installed, and I open the Expo app manually, I am able to run the app.

I did find that if I set detached=false in app.json, exp would at least try to install the Expo app if it wasn’t already installed, but it still used the URI scheme to launch, and thus would not launch in Expo. If I removed the scheme entirely from app.json, only then would it work just as it did prior to detaching.

I guess I could create an alternate app.json, but figured I’d check around for a better way first. Thank you!

Hi! Yes, the expected behavior is to run your detached Debug binary directly from Xcode/Android Studio, and to stop using the Expo Client iOS app. That’s because we can no longer safely assume your project’s JS is compatible with the native code powering Expo Client.

You might be able to run your detached app from within Expo Client if you’ve never made any breaking native changes. Because this workflow is so volatile, we don’t document or explicitly support it. It would just be too difficult for us to isolate the differences in people’s native code for them. But there’s nothing stopping you from doing it.

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