ios中UIWebview中加载本地文件

   [super viewDidLoad];
      webview=[[UIWebView alloc] initWithFrame:self.view.bounds];
    [self.view addSubview: webview];

    [webview release];
    // Do any additional setup after loading the view, typically from a nib.
//沙盒中读取文件
    NSString *doc=[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    doc=[doc stringByAppendingPathComponent:@"liuyan.html"];
    NSLog(@"%@",doc);

    NSURL *url=[NSURL fileURLWithPath:doc];
    NSLog(@"%@",url);
   NSURLRequest *request=[NSURLRequest requestWithURL:url];
    [webview loadRequest:request];
}