get the name and path of the frontmost window using the carbon mac os accessibility api

axInfoForProcessIdentifier.m

// http://stackoverflow.com/questions/2107657/mac-cocoa-getting-a-list-of-windows-using-accessibility-api
// http://stackoverflow.com/questions/853833/how-can-my-app-detect-a-change-to-another-apps-window
// http://cocoatutorial.grapewave.com/tag/axuielementcopyattributevalue/
- (NSDictionary *)axInfoForProcessIdentifier:(NSNumber *)processIdentifier
{
  NSMutableDictionary *ret = [NSMutableDictionary dictionaryWithCapacity:2];
  pid_t pid = (pid_t) [processIdentifier integerValue];
  AXUIElementRef app = AXUIElementCreateApplication(pid);
  AXUIElementRef frontWindow = nil;
  NSString *title = nil;
  NSString *path = nil;
  AXError err;

  // get the focused window for the application
  err = AXUIElementCopyAttributeValue(app, kAXFocusedWindowAttribute,
                                      (CFTypeRef *) &frontWindow);
  if (err == kAXErrorSuccess) {
    // get the title for the window
    err = AXUIElementCopyAttributeValue(frontWindow, kAXTitleAttribute, (CFTypeRef *) &title);
    if (err == kAXErrorSuccess) {
      [ret setObject:title forKey:@"title"];
      [title autorelease];
    }
    
    // get the document path for the window
    err = AXUIElementCopyAttributeValue(frontWindow, kAXDocumentAttribute, (CFTypeRef *) &path);
    if (err == kAXErrorSuccess) {
      [ret setObject:path forKey:@"path"];
      [path autorelease];
    }

    CFRelease(frontWindow);
  }

  CFRelease(app);
  return ret;
}