UGUI,使用ScrollView时，解决自适应屏幕尺寸问题

在Unity移动应用开发中，手机的横屏和竖屏，会导致屏幕尺寸发生变化，为了自适应屏幕尺寸，需要代码监听屏幕尺寸变化，并对GridLayoutGroud做相应设置。
实现方式如下：
步骤一：

步骤二：

实现代码：
UI对象控制类

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
public class UIManager : MonoBehaviour {
    public RectTransform scrollView;
    public GridLayoutGroup glg;

    private void OnEnable()
    {
        SizeManager.Instance.OnSizeValueChange += OnSizeValueChange;
    }

    private void OnDisable()
    {
        SizeManager.Instance.OnSizeValueChange -= OnSizeValueChange;
    }
    private void OnSizeValueChange(int width, int hight)
    {
        scrollView.sizeDelta = new Vector2(width, hight);
        glg.cellSize = new Vector2(width,glg.cellSize.y);
    }

    // Update is called once per frame
    void Update () {

    }

}

屏幕尺寸监听类

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class SizeManager : MonoBehaviour {
    public System.Action<int, int> OnSizeValueChange;
    private static SizeManager instance;
    // Use this for initialization
    void Start () {

    }

    // Update is called once per frame
    void Update () {

    }
    string debugStr;
    public GUIStyle style;
    float currentWidth;
    float currentHight;

    public static SizeManager Instance
    {
        get
        {
            if (instance == null) instance = GameObject.FindObjectOfType();
            return instance;
        }
    }

    private void OnGUI()
    {
        debugStr ="width "+ Screen.width + " hight= " + Screen.height;
        if (currentWidth != Screen.width || currentHight != Screen.height)
        {
            if (OnSizeValueChange != null)
            {
                OnSizeValueChange(Screen.width, Screen.height);
                Debug.Log("尺寸有变化....");
            }
            currentWidth = Screen.width;
            currentHight = Screen.height;
        }
        GUI.Label(new Rect(100,100,200,50), debugStr, style);
    }
}