title: Xcode LLDB breakpoint conditions - can I break on C function values?
body: <p>The iOS SDK is giving me warnings about some code (possibly some 3rd party API I'm using) that is making CG calls with a <code>nil</code> context. </p>
  
  <p>So I want to set up a symbolic breakpoint on one of these calls, and have it break when the passed context is <code>nil</code>. For example, if <code>CGContextSetBlendMode(context, mode)</code> is called with a <code>nil</code> context.</p>
  
  <p>I've created a Symbolic breakpoint with a condition of <code>context == nil</code>, but the debugger keeps telling me it's an invalid condition. </p>
  
  <p>Has anyone used breakpoints and conditions to stop of C functions calls? How did you specify the condition? </p>