Could not find the built application bundle at build/ios/iphoneos/Runner.app

Refer:

You are running flutter run and you are having this problem.

You might have updated the Display Name from Runner to your app name

To make it work, we need to update the Display Name to Runner back (General tab).

Xcode -> Runner -> Runner (under Targets) -> General -> Display Name (Under Identity)

Note: Changing this will not effect your app’s display name.