You do not submit your code to Apple. They do run some automated scans on your binary for calls to undocumented API's, and they do run your app and check for certain issues that are important to Apple. It's an approval process, not a testing process.
Again, I haven't touched an iPhone in my life, but this was the reason I've heard apps in Apple's App Store is better than apps in Android's App Store. There could be other reasons, but I thought it had to do with Apple's involvement.
Keep downvoting me; I don't care. I'm asking honest (and I guess dumb) questions.
