Question

在我的应用程序中使用UIWebView，我似乎无法释放它正在使用的内存。我有一个UIButton，它加载一个保存UIWebView的视图控制器。当加载webView时，Real Memory（使用Instruments检查它）会上升，但在我试图释放它之后不会降低。

按下按钮时：

if（childBroswer！= null）

        {
            childBroswer.Dispose();
            childBroswer = null;
        }

        childBroswer = new ChildBrowser(url);

        AppDelegate d = (AppDelegate)UIApplication.SharedApplication.Delegate;

        if ( d.rootNavigationController.RespondsToSelector(
            new MonoTouch.ObjCRuntime.Selector("presentViewController:animated:completion:")))
        {
                d.rootNavigationController.PresentViewController(childBroswer, true, null);
        }
        else
        {
            d.rootNavigationController.PresentModalViewController(childBroswer, true);
        }

儿童浏览器类：

 public partial class ChildBrowser : UIViewController
{
    public string _url {get;set;}
    UIActivityIndicatorView activityIndicator;
    UIWebView webBrowser;
    NSUrl nsURL;
    NSUrlRequest nsURLRequest;

    public ChildBrowser (string url) : base ("ChildBrowser", null)
    {
        nsURL = new NSUrl(url);
        nsURLRequest = new NSUrlRequest(nsURL);
    }

    public override void DidReceiveMemoryWarning ()
    {
        // Releases the view if it doesn't have a superview.
        base.DidReceiveMemoryWarning ();

        // Release any cached data, images, etc that aren't in use.
    }

    public override void ViewDidLoad ()
    {
        base.ViewDidLoad ();

        if (webBrowser == null)
        {
            webBrowser = new UIWebView(new RectangleF(0,41,320,380));
        }

        this.Add(webBrowser);

        webBrowser.LoadFinished += (object sender, EventArgs e) => {
            activityIndicator.StopAnimating();
        } ;

        webBrowser.LoadStarted += (object sender, EventArgs e) => {

            if (activityIndicator == null)
            {
                activityIndicator = new  UIActivityIndicatorView(new RectangleF(UIScreen.MainScreen.Bounds.Width / 2 - 50,
                                                                                UIScreen.MainScreen.Bounds.Height / 2 - 30,100,100));
                activityIndicator.Color = UIColor.Black;
            }

            activityIndicator.StartAnimating();
            this.Add(activityIndicator);
        } ;

        webBrowser.LoadHtmlString("<html><head></head><body></body></html>",null);   //stringByEvaluatingJavaScriptFromString:@"document.body.innerHTML = \"\";"];
        webBrowser.LoadRequest(nsURLRequest);

        closeBrowser.TouchUpInside +=  handleClose;


        // Perform any additional setup after loading the view, typically from a nib.
    }

    private void handleClose(object sender, EventArgs e)
    {
        webBrowser.Delegate = null;
        webBrowser.StopLoading();
        webBrowser.Dispose();

        DismissViewController(true,delegate {
            closeBrowser.TouchUpInside -=  handleClose;
            webBrowser.RemoveFromSuperview();
            this.Dispose();
        } );
    }

    public override void ViewWillAppear (bool animated)
    {
        base.ViewWillAppear (animated);


    }

    public override void ViewDidDisappear(bool animated)
    {
        base.ViewDidDisappear(true);
        //webBrowser.RemoveFromSuperview();
    }

    public void webViewDidFinishLoad(UIWebView webView)
    {
        //string u = "";
    }

    protected override void Dispose(bool disposing) 
    {
        ReleaseDesignerOutlets();
        base.Dispose(disposing);
    }

我缺少什么？

谢谢！

Answer 1

调用Dispose时，不回收原生对象的内存。调用Dispose只会删除托管的引用 - 但是ObjC运行时（引用计数）也不会释放该对象，直到没有 native 引用为止。有关详细信息，请参阅此Q&A

这意味着代码如：

this.Add(webBrowser);

将创建这样的本机引用，并且很可能（即如果未在其他地方删除），只要webBrowser处于活动状态，就可以使this实例保持活动状态。如果你保留Add那么你的内存使用量会继续增长。

Answer 2

我是OP - 似乎释放UIWebView的内存使用非常困难，即使在Objective-C中这样做。

我最终做了什么，但没有解决问题，但改进了内存释放，在关闭UIWebView时添加了以下几行：

NSUrlCache.SharedCache.RemoveAllCachedResponses（）;

        NSUrlCache.SharedCache.DiskCapacity = 0;

        NSUrlCache.SharedCache.MemoryCapacity = 0;

        webView.LoadHtmlString("",null);

        webView.EvaluateJavascript("var body=document.getElementsByTagName('body')[0];body.style.backgroundColor=(body.style.backgroundColor=='')?'white':'';");

        webView.EvaluateJavascript("document.open();document.close()");

        webView.StopLoading();

        webView.Delegate = null;

        webView.RemoveFromSuperview();

        webView.Dispose();

monotouch配置UIWebView

2 个答案: