To check for leaks, you use leaks or Instruments. To check for obvious (or less obvious) bugs, you use gcc and LLVM options, or you use the Build and Analyze feature of Xcode. To check that your code works, you test it. But what do you use to check the resources of the bundle of your application? Say hello to Cong. Cong checks multiple points and details that can seem obvious but which are not always known by everyone. Your application may be running fine, may have won Awards and still be not perfect. For instance, did you know that there is a limited set of characters allowed for a bundle identifier and that '_' (underscore) is not one of them? Did you know that the recommended encoding for .strings files is UTF-16? Did you know that the CFBundleGetInfoString key is deprecated for Info.plist files?