Possible solution to "Challenge: Closing Loopholes for Cheaters"

This is one possible solution to the first challenge in chapter 6. Hopefully this helps someone struggling with this challenge. My solution was to create a ViewModel for CheatActivity called CheatViewModel

Note: this is only for persisting UI state for a configuration change, not a process death scenario.

CheatActivity.kt:

package com.bignerdranch.android.geoquiz

import android.app.Activity
import android.content.Context
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.TextView
import androidx.lifecycle.ViewModelProviders

private const val EXTRA_ANSWER_IS_TRUE = "com.bignerdranch.android.geoquiz.answer_is_true"
const val EXTRA_ANSWER_SHOWN = "com.bignerdranch.android.geoquiz.answer_shown"

class CheatActivity : AppCompatActivity() {

    private var answerIsTrue = false

    private lateinit var answerTextView: TextView
    private lateinit var showAnswerButton: Button

    private val cheatViewModel: CheatViewModel by lazy {
        ViewModelProviders.of(this).get(CheatViewModel::class.java)
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_cheat)

        answerIsTrue = intent.getBooleanExtra(EXTRA_ANSWER_IS_TRUE, false)

        answerTextView = findViewById(R.id.answer_text_view)
        showAnswerButton = findViewById(R.id.show_answer_button)


        showAnswerButton.setOnClickListener {
            val answerText = when {
                answerIsTrue -> R.string.true_button
                else -> R.string.false_button
            }
            answerTextView.setText(answerText)
            setAnswerShownResult()
            cheatViewModel.answerWasClicked = true
        }

        if (cheatViewModel.answerWasClicked) {
            answerTextView.setText(R.string.true_button)
            setAnswerShownResult()
        }
    }

    private fun setAnswerShownResult() {
        val data = Intent().apply {
            putExtra(EXTRA_ANSWER_SHOWN, true)
        }
        setResult(Activity.RESULT_OK, data)
    }

    companion object {
        fun newIntent(packageContext: Context, answerIsTrue: Boolean): Intent {
            return Intent(packageContext, CheatActivity::class.java).apply {
                putExtra(EXTRA_ANSWER_IS_TRUE, answerIsTrue)
            }
        }
    }

}

CheatViewModel.kt:

package com.bignerdranch.android.geoquiz

import androidx.lifecycle.ViewModel

class CheatViewModel: ViewModel() {

    var answerWasClicked = false
    
}

Worked pretty well for me thanks a lot for sharing!