一、直接在編輯器Inspector上新增一個元件。

二、在指令碼中使用AddComponent函式新增一個元件，例如：

using UnityEngine;
using System.Collections;

public class Test : MonoBehaviour {
    private CanvasGroup m_CanvasGroup;
    void Start()
    {
        m_CanvasGroup = GetComponent<CanvasGroup> ();
        if(m_CanvasGroup == null
 
){
            gameObject.AddComponent<CanvasGroup> ();
            m_CanvasGroup = GetComponent<CanvasGroup> ();
        }
    }
}

官方例項：

    // Adds the sphere collider to the game object
    SphereCollider sc = gameObject.AddComponent("SphereCollider") as SphereCollider;
public Component AddComponent
 
(Type componentType);

三、利用RequireComponent新增一個元件。

using UnityEngine;
using System.Collections;
using UnityEngine.UI;

[RequireComponent(typeof(CanvasGroup))]
[RequireComponent(typeof(Image))]
public class Test : MonoBehaviour {
    private CanvasGroup m_CanvasGroup;
    private Image m_Image;
    void
 
 Start()
    {
        m_CanvasGroup = GetComponent<CanvasGroup> ();
        m_Image = GetComponent<Image> ();
    }
}

RequireComponent：這個類一定需要哪些元件，如果目前這些元件沒有被加上，就自動加上。

官方例項：

using UnityEngine;
// The GameObject requires a Rigidbody component
[RequireComponent (typeof (Rigidbody))]
public class PlayerScript : MonoBehaviour {
    Rigidbody rb;

    void Start() {
        rb = GetComponent<Rigidbody>();
    }
    void FixedUpdate()  {
        rb.AddForce(Vector3.up);
    }
}
public RequireComponent(Type requiredComponent);

public RequireComponent(Type requiredComponent, Type requiredComponent2);

public RequireComponent(Type requiredComponent, Type requiredComponent2, Type requiredComponent3);

–Rocky