Could not launch process launch failed: timed out waiting for app to launch

I had this problem when I used a Distribution certificate instead of Developer one when running the app from Xcode. You may check it out your target --> Build Settings --> Code signing.

As @AndyDynn pointed out in his comment: Make sure you do this on the "Target" build settings and not just the "Project" build settings.

I literally restarted my iPad, that was connected for testing the app, and that resolved the issue.

To run your app on a device, you will perform these tasks that follow:

1. Request a development certificate.

2. Add your device to the portal.

3. Code sign your app.

4. Launch your app on the device.

For more detail check this