Scene management: verify if a scene exists?

Is there any way to verify if a given string actually represents a legitimate scene?

Currently if I call SceneManager.LoadScene(levelName) and that level name doesn't refer to a legitimate scene that has been added to the scenes in the build, then this triggers an error and my game stops because it is expecting something to load that never will.

Is there any way to just test a given string to see if it is a legitimate level or not, rather than committing to load something that doesn't exist?
I can't seem to find a function for this within the scene manager.

 

Would this work?
https://docs.unity3d.com/ScriptReference/SceneManagement.SceneManager.GetSceneByName.html

You can check the "isValid" property on the returned scene object:
https://docs.unity3d.com/ScriptReference/SceneManagement.Scene.html

 

Okay, I'm not getting proper results from the "isValid" check.

I tried

if (SceneManager.GetSceneByName(loadThisLevel).IsValid())

but it always results in a false statement.
The levels I am checking are legitimate scenes, and if I bypass the above code they load just fine.

 

Because it only works if the scene is loaded. You don't have name if you don't have the scene loaded.
https://docs.unity3d.com/ScriptReference/SceneManagement.SceneManager.GetSceneByName.html

You can use the scene path or scene build index to check scenes in the valid scenes in the build settings:

Code (CSharp):

1.         for (var i = 0; i < SceneManager.sceneCountInBuildSettings; i++)
2.         {
3.             Debug.Log(i);
4.             var x = SceneUtility.GetScenePathByBuildIndex(i);
5.             Debug.Log(x);
6.         }
7.  

 

Old thread but as I was struggling with this myself, this was the first google result so lets get a definitive answer for future references!
As suggested by @Lurking-Ninja , the solution is using:

Code (CSharp):

1. int buildIndex = SceneUtility.GetBuildIndexByScenePath("path or name of the scene");

If the scene doesn't exist (or wasn't included in the build) the buildIndex value will be -1 , so you can check this out before actually trying to load the scene and cancel if the build index is less than zero

 

Following @atomicjoe move
And if we need an editor only answer :

Code (CSharp):

1.  
2. using UnityEditor;
3.  
4. public static bool IsSceneNameInProject(string named)
5. {
6.     foreach (EditorBuildSettingsScene scene in EditorBuildSettings.scenes) {
7.         if (scene.enabled) {
8.             if (scene.path.Contains("/" + named + ".unity")) {
9.                 return true;
10.             }
11.         }
12.     }
13.     return false;
14. }

Or with linq if we already use it

Code (CSharp):

1.  
2. using System.Linq;
3. using UnityEditor;
4.  
5. public static bool IsSceneInProject(string named)
6. {
7.        
8.     return EditorBuildSettings.scenes.Any(scene => scene.enabled && scene.path.Contains("/" + named + ".unity"));
9.  
10. }

 

And how do I find out that the scene has already been loaded from the Asset Bundle, and that it is already valid and not to download it a second time?
it's just that this method did not work in my case, after loading the scene from the bundle, I always get -1 in her name

 

I guess this method is only valid for scenes included in the build process, not the ones loaded from Asset Bundles.
But since Asset Bundles are loaded manually, you can keep track of it manually: as soon as the Asset Bundle is correctly loaded, you can expect the scene to be loaded too.