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>  
    /// 加載完場景后就會跳轉  
    /// </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 你正在讀取的場景的進度值  0---0.9    
        // 如果當前的進度小于0.9，說明它還沒有加載完成，就說明進度條還需要移動    
        // 如果，場景的數據加載完畢，async.progress 的值就會等于0.9  
        if(async.progress < 0.9f)  
        {  
            toProcess = (int)async.progress * 100;  
        }  
        else  
        {  
            toProcess = 100;  
        }  
        // 如果滑動條的當前進度，小于，當前加載場景的方法返回的進度   
        if(nowProcess < toProcess)  
        {  
            nowProcess++;  
        }  
  
        processBar.value = nowProcess / 100f;  
        // 設置為true的時候，如果場景數據加載完畢，就可以自動跳轉場景   
        if(nowProcess == 100)  
        {  
            async.allowSceneActivation = true;  
        }  
    }  
}  

來自http://blog.csdn.net/qq_28221881/article/details/53674445#comments