What-Unity-Does-Not-Tell-You

Unity APIs that may be useful but not mentioned in the documentation.

Full lists of undocumented APIs

Tip: Press Ctrl+F on the list page to search for the keyword of the content you are looking for.

• Unity 6000.0.23f1 Undocumented APIs
• Unity 2022.3.0f1 Undocumented APIs
• Unity 2021.3.0f1 Undocumented APIs
• Unity 2020.3.48f1 Undocumented APIs
• Unity 2019.4.40f1 Undocumented APIs

Frequently Used APIs

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Draw buttons on the header area of the EditorWindow:

// Unity message method
// Put in your EditorWindow class
void ShowButton(Rect position)

Sample Code

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Open asset in a custom EditorWindow when double-clicking:

[CreateAssetMenu(fileName = nameof(MyCustomAsset), menuName = "Tests/My Custom Asset")]
public class MyCustomAsset : ScriptableObject { }

public class MyCustomAssetEditorWindow : EditorWindow
{
    [OnOpenAsset]
    static bool OnOpenAsset(int instanceID, int line, int column)
    {
        if (EditorUtility.InstanceIDToObject(instanceID) is MyCustomAsset myAsset)
        {
            var window = GetWindow<MyCustomAssetEditorWindow>();
            window.SetTarget(myAsset);
            window.Focus();

            // Returning true indicates that the open operation has been processed
            // and the callback is not continued.
            return true;
        }

        // Returning false indicates that the open operation cannot be handled here,
        // and other methods in the callback should be continued.
        return false;
    }

    public void SetTarget(MyCustomAsset target)
    {
        // Do anything you want here.
        titleContent = new GUIContent(target.name);
        Debug.Log($"Open {target}.");
    }
}

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Modify menu items dynamically, no need for MenuItemAttribute:

The UnityEditor.Menu class provides some methods for dynamically managing menu items, but these methods are internal and can be called through reflection.

Here is a utility class that simplifies reflection: DynamicMenuItem.cs.

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Keep serialized data after changing name or namespace of type:

Similar to UnityEngine.Serialization.FormerlySerializedAsAttribute .

UnityEngine.Scripting.APIUpdating.MovedFromAttribute

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Read/Write assets in Library/ProjectSettings/UserSettings folder:

UnityEditorInternal.InternalEditorUtility.LoadSerializedFileAndForget()

UnityEditorInternal.InternalEditorUtility.SaveToSerializedFileAndForget()

Usually, the UnityEditor.ScriptableSingleton<T> type can be used to create a singleton configuration asset stored in the Library folder, eliminating the need to use the above two methods.

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Many helpful editor utility functions:

UnityEditorInternal.InternalEditorUtility

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To be continued...