What "kernel level C function" does Frenzapp use to detect running iOS processes?

According to this iphonedevsdk.com forum post, Frenzapp uses two methods to detect other apps installed on an iOS device:

1. UIApplication canOpenUrl: to check if known custom URL schemas can be opened
2. A "kernel level C function", that is "authorized by apple".

What "kernel le开发者_运维百科vel C function" are they using? Where is it documented?

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Thanks to Vladamir and Stephen Darlington for commenting and pointing us at what is most likely the answer:

• The kernel C function is sysctl()
• It's documented on Apple's iOS Developer site
• You need to call it with a certain set of arguments to get the list of running processes (ids and strings)
  • See Vladimir's previous answer or This post for example code

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Right, though the process list is both very limited and presupposes that the process is indeed "running" in the background.

The key for discovery is having a large enough inventory of both process names (but the background tasking can only go so far...) and URLhandlers. And only a few companies in the World (if that many) outside of Apple can actually do this well.

And of course, the Springboard has an open-socket protocol that lets the App Store app (and potentially other apps) query whether an app is installed or not... but that's actually a much tougher one to crack.