How do I find Assembly Reference?

Question

I am currently making a 2D Platformer in Unity, and I still can't move the character because of the errors I have in this code. I am not sure how to find the assembly reference, so if someone could please explain it, that would be great.

Here's the error: Error CS0234 The type or namespace name 'IActiveBuildTargetChanged' does not exist in the namespace 'UnityEditor.Build' (are you missing an assembly reference?)

Thanks

using System;
    using UnityEngine;
    #if UNITY_EDITOR
using UnityEditor;
#endif

namespace UnityStandardAssets.Utility
{
#if UNITY_EDITOR

    [ExecuteInEditMode]
#endif
    public class PlatformSpecificContent : MonoBehaviour
#if UNITY_EDITOR
        , UnityEditor.Build.IActiveBuildTargetChanged
#endif
    {
        private enum BuildTargetGroup
        {
            Standalone,
            Mobile
        }

        [SerializeField]
        private BuildTargetGroup m_BuildTargetGroup;
        [SerializeField]
        private GameObject[] m_Content = new GameObject[0];
        [SerializeField]
        private MonoBehaviour[] m_MonoBehaviours = new MonoBehaviour[0];
        [SerializeField]
        private bool m_ChildrenOfThisObject;

#if !UNITY_EDITOR
    void OnEnable()
    {
        CheckEnableContent();
    }
#else
        public int callbackOrder
        {
            get
            {
                return 1;
            }
        }
#endif

#if UNITY_EDITOR

        private void OnEnable()
        {
            EditorApplication.update += Update;
        }


        private void OnDisable()
        {
            EditorApplication.update -= Update;
        }

        public void OnActiveBuildTargetChanged(BuildTarget previousTarget, BuildTarget newTarget)
        {
            CheckEnableContent();
        }

        private void Update()
        {
            CheckEnableContent();
        }
#endif


        private void CheckEnableContent()
        {
#if (UNITY_IPHONE || UNITY_ANDROID || UNITY_WP8 || UNITY_TIZEN || UNITY_STV )
        if (m_BuildTargetGroup == BuildTargetGroup.Mobile)
        {
            EnableContent(true);
        } else {
            EnableContent(false);
        }
#endif

#if !(UNITY_IPHONE || UNITY_ANDROID || UNITY_WP8 || UNITY_TIZEN || UNITY_STV )
            if (m_BuildTargetGroup == BuildTargetGroup.Mobile)
            {
                EnableContent(false);
            }
            else
            {
                EnableContent(true);
            }
#endif
        }


        private void EnableContent(bool enabled)
        {
            if (m_Content.Length > 0)
            {
                foreach (var g in m_Content)
                {
                    if (g != null)
                    {
                        g.SetActive(enabled);
                    }
                }
            }
            if (m_ChildrenOfThisObject)
            {
                foreach (Transform t in transform)
                {
                    t.gameObject.SetActive(enabled);
                }
            }
            if (m_MonoBehaviours.Length > 0)
            {
                foreach (var monoBehaviour in m_MonoBehaviours)
                {
                    monoBehaviour.enabled = enabled;
                }
            }
        }
    }
}

Answer 1

Use Google.

Googling IActiveBuildTargetChanged gives us the first result, which says this interface is in UnityEditor.Build starting with version 2017.1.

So include that assembly if you need to, and add a using statement to the top of your file if necessary.

If you already have this assembly referenced, verify your version. You might be using an older version of the assembly.