unity异步加载场景的代码

using UnityEngine;
using System.Collections;
using UnityEngine.UI;
using UnityEngine.SceneManagement;
public class LoadingScene : MonoBehaviour {
public Slider processBar;

private AsyncOperation async;  

private int nowProcess;  

void Start()  
{  
    StartCoroutine(loadScene());  
}  
/// <summary>  
/// 加载完场景后就会跳转  
/// </summary>  
/// <returns></returns>  
IEnumerator loadScene()  
{  
    async = SceneManager.LoadSceneAsync("sceneName");  
    async.allowSceneActivation = false;  
    yield return async;  
}  

void Update()  
{  
    if(async == null)  
    {  
        return;  
    }  

    int toProcess;  
    // async.progress 你正在读取的场景的进度值  0---0.9    
    // 如果当前的进度小于0.9，说明它还没有加载完成，就说明进度条还需要移动    
    // 如果，场景的数据加载完毕，async.progress 的值就会等于0.9  
    if(async.progress < 0.9f)  
    {  
        toProcess = (int)async.progress * 100;  
    }  
    else  
    {  
        toProcess = 100;  
    }  
    // 如果滑动条的当前进度，小于，当前加载场景的方法返回的进度   
    if(nowProcess < toProcess)  
    {  
        nowProcess++;  
    }  

    processBar.value = nowProcess / 100f;  
    // 设置为true的时候，如果场景数据加载完毕，就可以自动跳转场景   
    if(nowProcess == 100)  
    {  
        async.allowSceneActivation = true;  
    }  
}  

}