using UnityEditor;
using UnityEngine;

public class MyScript : MonoBehaviour
{
 public bool visible;
 public int i = 1;
}

[CustomEditor(typeof(MyScript))]
public class MyScriptEditor : Editor
{
 public override void OnInspectorGUI()
 {
 var myScript = target as MyScript;

 if (myScript)
 {
 myScript.visible = GUILayout.Toggle(myScript.visible, "visible i");

 if (myScript.visible)
 myScript.i = EditorGUILayout.IntField("i : ", myScript.i);
 }
 }
}