https://github.com/udacity/andfun-kotlin-about-me/blob/8045d5ae0397d010fbf6944e640746aeb516933e/app/src/main/java/com/example/android/aboutme/MainActivity.kt#L42

https://github.com/ojedavidea/MAD/blob/master/apps/AboutMe/app/src/main/java/com/example/android/aboutme/MainActivity.kt#L17

I have tried some improvement in the data id from:

 binding.apply {
            nicknameText.text = binding.nicknameEdit.text
            invalidateAll()
            nicknameEdit.visibility = View.GONE
            doneButton.visibility = View.GONE
            nicknameText.visibility = View.VISIBLE
        }

to:

binding.apply {
            nickname_text.text = binding.nickname_edit.text
            invalidateAll()
            nickname_edit.visibility = View.GONE
            done_button.visibility = View.GONE
            nickname_text.visibility = View.VISIBLE
        }

But the errors remain:

e: /Users/ojedavidea/AndroidStudioProjects/AboutMe/app/src/main/java/com/example/android/aboutme/MainActivity.kt: (12, 36): Unresolved reference: databinding

e: /Users/ojedavidea/AndroidStudioProjects/AboutMe/app/src/main/java/com/example/android/aboutme/MainActivity.kt: (17, 35): Unresolved reference: ActivityMainBinding

e: /Users/ojedavidea/AndroidStudioProjects/AboutMe/app/src/main/java/com/example/android/aboutme/MainActivity.kt: (32, 25): Unresolved reference: it

e: /Users/ojedavidea/AndroidStudioProjects/AboutMe/app/src/main/java/com/example/android/aboutme/MainActivity.kt: (42, 13): Unresolved reference: invalidateAll