After detach project. how can i bundle js to generate apk/ipa

hi everybody!
i have detached project. now i want to generate ipa.

  1. pod install
  2. open in xcode
  3. generate/run play button.
    i saw app will load a few minutes. this is not i want.
    'react-native bundle ’ might make a js. then do something in xcode.
    anyone can help me ? think you all!!!