Any iPhone apps to test the touchscreen? I've been playing an iPhone game for about a week and today the phone didn't detect some of my swipes.  It still detected most of my swipes, but on a few occasions I swiped and nothing happened.  I did drop my phone on a carpeted floor yesterday so I wonder if that has anything to do with it.

Are there any apps that let you test the iPhone touchscreen?  I would think someone has developed an app that lets you touch/swipe anywhere on the screen and it gives you visual feedback that it detected your touch/swipe.  I searched in the App Store and didn't see anything.

I found this answer that said there are a few utilities that let you test the responsiveness of your iPhone, but it didn't mention the names of those utilities.  It also mentioned a web site named Sparky, but I went there on my iPhone and couldn't do anything there.

I have an iPhone 4S running iOS 6.1.3.
Sparky works for testing multitouch, so you can try different areas of the screen by holding one finger in a place you know works and move the other elsewhere. If the line breaks, then the second finger is in a location that doesn't work. You can test it full screen (without the Safari UI but the status bar is still present) by adding it to the home screen.