title: How do I set a symbolic breakpoint on _WebThreadLockFromAnyThread in Xcode?
body: <p>I'm using Xcode 4.3.2 with lldb as my debugger.</p>
  
  <p>I have inherited a project that contains code that is calling UIKit from secondary threads, as shown by these log messages:</p>
  
  <blockquote>
    <p>2012-05-02 21:48:14.603 Appname Dev[77594:16e0f] void
    _WebThreadLockFromAnyThread(bool), 0x8d5f810: Obtaining the web lock from a thread other than the main thread or the web thread. UIKit
    should not be called from a secondary thread.</p>
  </blockquote>
  
  <p>I have cleaned up most of the code that was making UIKit calls from secondary threads, but I am still occasionally seeing this message in the logs. The app is not crashing, so it's difficult to pinpoint where the problem lies.</p>
  
  <p>I'd like to set a breakpoint on <code>_WebThreadLockFromAnyThread</code>, but when I try to set a symbolic breakpoint using:</p>
  
  <pre><code>b _WebThreadLockFromAnyThread
  </code></pre>
  
  <p>the debugger tells me:</p>
  
  <blockquote>
    <p>breakpoint set --name '_WebThreadLockFromAnyThread' Breakpoint
    created: 12: name = '_WebThreadLockFromAnyThread', locations = 0
    (pending) WARNING:  Unable to resolve breakpoint to any actual
    locations.</p>
  </blockquote>
  
  <p>I've also tried creating the symbolic breakpoint using the UI in the breakpoint navigator, but I'm not sure what to enter for the module. When I leave the module blank, the breakpoint is created but it's still not breaking when the log message appears in the debug console.</p>
  
  <p>Can anyone tell me how I can go about adding a breakpoint on <code>_WebThreadLockFromAnyThread</code>, and also how I would determine what the defining module is for this symbol?</p>