It's hard for app creators to stand out in the insanely crowded marketplace that is the App Store. With dozens if not hundreds of new apps going up every day, many get lost. But one thing that almost always works is controversy. Although Apple does vet software that goes up on its platform, it's not a foolproof process. Every once in a while, something will sneak through that skirts the line of decency for one reason or another.

Apple's content guidelines are, on the surface, pretty clear. Apps that are sexually explicit, defamatory, or portray realistic violence are pulled right away. In addition, there's a ban on apps that could damage the hardware, as well as controls on how user data is read and spread. The basic stuff that ensures malicious software doesn't open either Apple or the end user to legal liability.

That said, there are always people looking to push the envelope. Since the opening of the App Store in 2008, dozens of enterprising software creators have floated apps that push up against these restrictions. Usually they get banned pretty quick, but some last long enough to bring a storm of public opprobrium down on themselves.

We found 10 iOS apps that courted controversy for better or for worse. Some allowed for your iPhone to become a gateway to a world of stalking, while others were just in extremely bad taste. We also analyze Apple's reaction to the apps, most of which were pulled from sale in a matter of days. Check it out in the slideshow.

(Android fans, meanwhile, can check out the Top 10 Most Controversial Android Apps.)