UIWebView加载HTML5-视频EXC_BAD_ACCESS崩溃

Question

在我们的iPad-App中，我们使用UIWebView从一个域中加载不同的站点，其中一些站点使用的是hml5-Video。没有视频的网站可以很好地加载。但是，当我加载一个包含HTML5视频的网站时，我的应用程序在使用EXC_BAD_ACCESS加载UIWebView的过程中有时会崩溃，有时不会。无论何时发生这样的崩溃，似乎都是在视频播放器被添加到站点的时候发生的。

我确实从Apple下载了UICatalog-Example，并且刚刚将WebViewController-Class中的Default-URL更改为包含html5-video的站点的URL。同样的结果。有时会崩溃，有时不会崩溃。

我还在Xcode (基于视图的应用程序-用于iPad)上创建了一个新项目，并且只在新项目的ViewController中添加了一个UIWebView。再一次..。加载包含html5-video的站点有时会导致崩溃，有时不会。

来自“新项目”VIEWCONTROLLER (实现)的代码：

- (void)viewDidLoad {
    [super viewDidLoad];

    self.myWebView = [[[UIWebView alloc] initWithFrame:CGRectMake(0, 0, 768, 1004)] autorelease];
    self.myWebView.backgroundColor = [UIColor whiteColor];
    self.myWebView.scalesPageToFit = YES;
    self.myWebView.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight);
    self.myWebView.delegate = self;
    [self.view addSubview: self.myWebView];

    [self.myWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.gelbeseiten.de/129103114849"]]];

    //More Sites with HTML5-Videos ...
    //[self.myWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.gelbeseiten.de/129103746403"]]];
    //[self.myWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.gelbeseiten.de/129105233646"]]];
}

- (void)viewDidUnload {
    [super viewDidUnload];

    self.myWebView = nil;
}

- (void)viewWillDisappear:(BOOL)animated {
    [self.myWebView stopLoading];
}

- (void)dealloc {
    myWebView.delegate = nil;
    [myWebView release];

    [super dealloc];
}

“新项目”VIEWCONTROLLER代码(表头)：

@interface WebViewTestViewController : UIViewController <UIWebViewDelegate> {
    UIWebView *myWebView;
}

@property (nonatomic, retain) UIWebView *myWebView;

设备日志：

Exception Type:  EXC_BAD_ACCESS (SIGBUS)
Exception Codes: KERN_PROTECTION_FAILURE at 0x00000098
Crashed Thread:  0

Thread 0 Crashed:
0   WebCore                         0x34c7d09e WebCore::RenderLayer::clippingRoot() const + 110
1   WebCore                         0x34c7cf2a WebCore::RenderLayer::childrenClipRect() const + 26
2   WebCore                         0x34c7ce0c WebCore::RenderWidget::setWidgetGeometry(WebCore::IntRect const&) + 40
3   WebCore                         0x34c5e0f8 WebCore::RenderWidget::updateWidgetPosition() + 320
4   WebCore                         0x34ba0170 WebCore::RenderView::updateWidgetPositions() + 144
5   WebCore                         0x34b97d16 WebCore::FrameView::performPostLayoutTasks() + 202
6   WebCore                         0x34b8a6c0 WebCore::FrameView::layout(bool) + 2116
7   WebCore                         0x34bc5244 WebCore::FrameView::forceLayout(bool) + 4
8   WebKit                          0x302c0c24 -[WebHTMLView layoutToMinimumPageWidth:height:maximumPageWidth:adjustingViewSize:] + 136
9   WebKit                          0x302c0b8e -[WebHTMLView layout] + 18
10  WebKit                          0x302c26f2 -[WebHTMLView(WebInternal) _layoutIfNeeded] + 50
11  WebKit                          0x302c2622 -[WebHTMLView(WebInternal) _web_layoutIfNeededRecursive] + 14
12  WebKit                          0x302c251e -[WebHTMLView(WebPrivate) viewWillDraw] + 50
13  CoreFoundation                  0x3581dfc0 -[NSObject(NSObject) performSelector:] + 12
14  CoreFoundation                  0x35826d4a -[NSArray makeObjectsPerformSelector:] + 382
15  WebCore                         0x34bb000c -[WAKView viewWillDraw] + 24
16  CoreFoundation                  0x3581dfc0 -[NSObject(NSObject) performSelector:] + 12
17  CoreFoundation                  0x35826d4a -[NSArray makeObjectsPerformSelector:] + 382
18  WebCore                         0x34bb000c -[WAKView viewWillDraw] + 24
19  CoreFoundation                  0x3581dfc0 -[NSObject(NSObject) performSelector:] + 12
20  CoreFoundation                  0x35826d4a -[NSArray makeObjectsPerformSelector:] + 382
21  WebCore                         0x34bb000c -[WAKView viewWillDraw] + 24
22  CoreFoundation                  0x3581dfc0 -[NSObject(NSObject) performSelector:] + 12
23  CoreFoundation                  0x35826d4a -[NSArray makeObjectsPerformSelector:] + 382
24  WebCore                         0x34bb000c -[WAKView viewWillDraw] + 24
25  WebKit                          0x302c24cc -[WebView(WebPrivate) viewWillDraw] + 56
26  WebCore                         0x34bafec0 WebCore::TileCache::prepareToDraw() + 36
27  WebCore                         0x34bafe6e -[TileLayer display] + 26
28  QuartzCore                      0x31079fb0 CALayerDisplayIfNeeded + 176
29  QuartzCore                      0x3106f56e CA::Context::commit_transaction(CA::Transaction*) + 214
30  QuartzCore                      0x3106f37c CA::Transaction::commit() + 184
31  QuartzCore                      0x31092f96 CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) + 46
32  CoreFoundation                  0x3580ac52 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 10
33  CoreFoundation                  0x3580aac6 __CFRunLoopDoObservers + 406
34  CoreFoundation                  0x358020c4 __CFRunLoopRun + 848
35  CoreFoundation                  0x35801c80 CFRunLoopRunSpecific + 224
36  CoreFoundation                  0x35801b88 CFRunLoopRunInMode + 52
37  GraphicsServices                0x320c84a4 GSEventRunModal + 108
38  GraphicsServices                0x320c8550 GSEventRun + 56
39  UIKit                           0x341dc322 -[UIApplication _run] + 406
40  UIKit                           0x341d9e8c UIApplicationMain + 664
41  WebViewTest                     0x00002c24 0x1000 + 7204
42  WebViewTest                     0x00002bd8 0x1000 + 7128

有人能给我出个主意吗？

先谢谢你，弗洛里安

Answer 1

这里有一个小技巧来覆盖这个崩溃。如果在加载视频内容之前稍微滚动一下webview，就可以避免崩溃。在从代码中尝试它之前，试着用手指在设备上滚动一下webView。现在它不会崩溃了。

在代码中，执行如下操作：

- (void)webViewDidFinishLoad:(UIWebView *)webView
{
  [webView stringByEvaluatingJavaScriptFromString:@"window.scrollTo(0, 10);"];
}

以通过javascript模拟webview上的滚动。滚动值可以低至1，因此用户根本不会注意到滚动。

Answer 2

告诉webview在webViewDidFinishLoad上评估任何JavaScript (或者根本不评估)：看起来是可行的(尽管很麻烦)。

- (void)webViewDidFinishLoad:(UIWebView *)webView
{
  [webView stringByEvaluatingJavaScriptFromString:@""];
}

Answer 3

看起来我已经解决了这个问题。我已经将所有HTML-5视频标签插入到Javascript中

function placeVideoTag() {
   var val = '<video />';
   var el = document.getElementById('video-id');
   el.innerHTML = val;
}

我要在UIWebView didFinishLoad中调用JS

- (void)webViewDidFinishLoad:(UIWebView *)aWebView {
   [aWebView stringByEvaluatingJavaScriptFromString:@"placeVideoTag()"];
}

在我的情况下效果很好。其他的建议对我不起作用。