Android device Back button not going back to last scene

Question

In Unity, I am trying to go back to the last scene by clicking the Device Android back button and not back to the main screen.

I tried to save the state of the last scene but I always get that the last scene is 0 instead of the correct scene number.

Here is my c# code:

 public class SceneLoader : MonoBehaviour {
 
     private static int lastScene;
 
 
     private void Update()
     {
         if (Input.GetKey(KeyCode.Escape))
         {
 
             Debug.Log("Last scene: "+ GetLastScene());
 
             SceneManager.LoadScene(GetLastScene());               
             return;
         }
     }
 
     public void LoadNextScene(int numberOfScene)
     {
         StartCoroutine(LoadAfterSeconds(numberOfScene));    
     }
 
     private IEnumerator LoadAfterSeconds(int numberOfScene)
     {            
         yield return new WaitForSeconds(1f);
         SceneManager.LoadScene(numberOfScene);
         SetLastScene(numberOfScene);
         gameObject.SetActive(true);
     }
 
     public static void SetLastScene(int level)
     {
         lastScene = level;
     }
 
     public static int GetLastScene()
     {
         return lastScene;
     }
 
 }

If I don't call SetLastScene at all, then lastScene is always 0 and so when I press the Android device back button or "Escape" it goes to main screen (number 0). But when I use SetLastScreen it always get the current scene number instead of the previous scene.

Thank you.

Answer 1

I have tested the code @HenBOMB but the SceneManagement.LoadLevel doesn't seem to work for me.

I have changed my code and now it works:

 public class SceneLoader : MonoBehaviour
 {
     private static int lastScene;
     private int currentScene;
 
     private void Awake()
     {
         currentScene = SceneManager.GetActiveScene().buildIndex;
     }
 
     private void Update()
     {
         BackButtonPressed();
     }
 
     public void LoadNextScene(int numberOfSceneToLoad)
     {
         StartCoroutine(LoadScene(numberOfSceneToLoad));
     }
 
     private IEnumerator LoadScene(int numberOfScene)
     {
         currentScene = SceneManager.GetActiveScene().buildIndex;
         SetLastScene(currentScene);
 
         yield return new WaitForSeconds(0.5f);
         SceneManager.LoadScene(numberOfScene);
         
     }
 
 
     private void BackButtonPressed()
     {
         if (Input.GetKey(KeyCode.Escape))
         {
 
             Debug.Log("Current scene: " + currentScene);
             Debug.Log("Last Scene (scene to load): " + GetLastScene());
 
             SceneManager.LoadScene(GetLastScene());
 
             currentScene = GetLastScene();
             lastScene -= lastScene;
             Debug.Log("Now the Current scene is: " + currentScene);
             Debug.Log("And the scene to load is: " + lastScene);
         }
     }
 
 
     public static void SetLastScene(int currentSceneToLastScene)
     {
         lastScene = currentSceneToLastScene;
     }
 
     public static int GetLastScene()
     {
         return lastScene;
     }
 
     public void QuitGame()
     {
         Application.Quit();
     }
 
 }

Answer 2

Answer by HenBOMB · Nov 28, 2018 at 11:08 PM

I think its because you never assigned the value of your 'lastScene', so it sets it as default 0. the script was kind of condusing to interpret so heres what i wrote:

 int currentScene;
 
 void Update(){
     if(Input.GetKeyDown(KeyCode.Escape)){
         StartCoroutine(LoadPreviousScene(1));
     }
 }
 IEnumerator LoadNextScene(float waitingTime){
     yield return new WaitForSeconds(waitingTime);
     currentScene++;
     SceneManagement.LoadLevel(currentScene);
 }
 IEnumerator LoadPreviousScene(float waitingTime){
     yield return new WaitForSeconds(waitingTime);
     currentScene--;
     SceneManagement.LoadLevel(currentScene);
 }
 int GetCurrentScene(){
     return current;
 }
  int GetNextScene(){
     return current++;
 }
  int GetPreviousScene(){
     return current--;
 }

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Android device Back button not going back to last scene

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