我的iPhone Objective-C代码如何在UIWebView中收到Javascript错误的通知？ [英] How can my iPhone Objective-C code get notified of Javascript errors in a UIWebView?

问题描述

我需要让我的iPhone Objective-C代码在UIWebView中捕获Javascript错误。这包括未捕获的异常，加载文件时的语法错误，未定义的变量引用等。

I need to have my iPhone Objective-C code catch Javascript errors in a UIWebView. That includes uncaught exceptions, syntax errors when loading files, undefined variable references, etc.

这是针对开发环境的，所以它不需要是SDK-kosher 。事实上，它只需要在模拟器上工作。

This is for a development environment, so it doesn't need to be SDK-kosher. In fact, it only really needs to work on the simulator.

我已经发现使用了一些隐藏的WebKit技巧，例如将Obj-C对象暴露给JS并拦截警报弹出窗口，但是这个仍然无法阻止我。

I've already found used some of the hidden WebKit tricks to e.g. expose Obj-C objects to JS and to intercept alert popups, but this one is still eluding me.

[注意：发布后我确实发现了一种使用调试的方法代表。有没有一种方法可以降低开销，使用错误控制台/网络检查器？]

[NOTE: after posting this I did find one way using a debugging delegate. Is there a way with lower overhead, using the error console / web inspector?]

推荐答案

我现在找到一种方法使用WebView中的脚本调试器挂钩（注意，不是UIWebView）。我首先必须继承UIWebView并添加如下方法：

I have now found one way using the script debugger hooks in WebView (note, NOT UIWebView). I first had to subclass UIWebView and add a method like this:

- (void)webView:(id)webView windowScriptObjectAvailable:(id)newWindowScriptObject {
    // save these goodies
    windowScriptObject = newWindowScriptObject;
    privateWebView = webView;

    if (scriptDebuggingEnabled) {
        [webView setScriptDebugDelegate:[[YourScriptDebugDelegate alloc] init]];
    }
}

接下来你应该创建一个包含类似方法的YourScriptDebugDelegate类这些：

Next you should create a YourScriptDebugDelegate class that contains methods like these:

// in YourScriptDebugDelegate

- (void)webView:(WebView *)webView       didParseSource:(NSString *)source
 baseLineNumber:(unsigned)lineNumber
        fromURL:(NSURL *)url
       sourceId:(int)sid
    forWebFrame:(WebFrame *)webFrame
{
    NSLog(@"NSDD: called didParseSource: sid=%d, url=%@", sid, url);
}

// some source failed to parse
- (void)webView:(WebView *)webView  failedToParseSource:(NSString *)source
 baseLineNumber:(unsigned)lineNumber
        fromURL:(NSURL *)url
      withError:(NSError *)error
    forWebFrame:(WebFrame *)webFrame
{
    NSLog(@"NSDD: called failedToParseSource: url=%@ line=%d error=%@\nsource=%@", url, lineNumber, error, source);
}

- (void)webView:(WebView *)webView   exceptionWasRaised:(WebScriptCallFrame *)frame
       sourceId:(int)sid
           line:(int)lineno
    forWebFrame:(WebFrame *)webFrame
{
    NSLog(@"NSDD: exception: sid=%d line=%d function=%@, caller=%@, exception=%@", 
          sid, lineno, [frame functionName], [frame caller], [frame exception]);
}

对此可能会产生很大的运行时影响，因为调试委托也可以提供进入和退出堆栈帧以及执行每行代码的方法。

There is probably a large runtime impact for this, as the debug delegate can also supply methods to be called for entering and exiting a stack frame, and for executing each line of code.

参见 http://www.koders.com/noncode/fid7DE7ECEB052C3531743728D41A233A951C79E0AE.aspx ，用于WebScriptDebugDelegate的Objective-C ++定义。

See http://www.koders.com/noncode/fid7DE7ECEB052C3531743728D41A233A951C79E0AE.aspx for the Objective-C++ definition of WebScriptDebugDelegate.

那些其他方法：

// just entered a stack frame (i.e. called a function, or started global scope)
- (void)webView:(WebView *)webView    didEnterCallFrame:(WebScriptCallFrame *)frame
      sourceId:(int)sid
          line:(int)lineno
   forWebFrame:(WebFrame *)webFrame;

// about to execute some code
- (void)webView:(WebView *)webView willExecuteStatement:(WebScriptCallFrame *)frame
      sourceId:(int)sid
          line:(int)lineno
   forWebFrame:(WebFrame *)webFrame;

// about to leave a stack frame (i.e. return from a function)
- (void)webView:(WebView *)webView   willLeaveCallFrame:(WebScriptCallFrame *)frame
      sourceId:(int)sid
          line:(int)lineno
   forWebFrame:(WebFrame *)webFrame;

请注意，这一切都隐藏在私有框架中，所以不要试图将其放入您提交给App Store的代码，并准备好一些hackery以使其工作。

Note that this is all hidden away in a private framework, so don't try to put this in code you submit to the App Store, and be prepared for some hackery to get it to work.

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