title: How can I find out what is changing an object (or a simple variable) in Xcode 4 / lldb?
body: <p>In some debuggers this is called "setting a trap" on a variable. What I want to do is trigger a breakpoint on any statement that changes the object. Or changes a property of the object.</p>
  
  <p>I have an NSMutableDictionary that gets a value/key added to it but I can't find any statement that could be doing that.</p>