CSHARP

custom editor unity

using UnityEngine;
using UnityEditor;

[CustomEditor(typeof(MyComponent))]
[CanEditMultipleObjects]
public class MyComponentEditor : Editor 
{    
    public override void OnInspectorGUI()
    {
        MyComponent myComponent = (MyComponent)target;
        
        DrawDefaultInspector();
        
        if(GUILayout.Button("MyButton"))
        {
        	myComponent.doSomething();
        }
    }
}

unity custom editor

// MapGenerator is class on which this custom editor will be called
using UnityEditor;
[CustomEditor(typeof(MapGenerator))]
public class Edit : Editor
{
    public override void OnInspectorGUI()
    {
        base.OnInspectorGUI(); 
        // if you remove |^|(base.OnInspectorGUI(); )
        // variable in inspector may not show up properly
        
        MapGenerator mapGenerator = (MapGenerator)target;
        mapGenerator.Function();
    }
}

// another approach it is called only if there is change in the value.

using UnityEditor;
[CustomEditor(typeof(MapGenerator))]
public class Edit : Editor
{
    public override void OnInspectorGUI()
    {
        MapGenerator mapGenerator = (MapGenerator)target;
        if(DrawDefaultInspector())
        {
           	mapGenerator.Function();
        }
    }
}