Apps can register custom URL schemes to enable other apps to open them, pass them data and even deep-link to within them. There is an official API called canOpenUrl: which will let you check if a particular URL scheme is registered on a particular device. So that, along with a database of public URL schemes published by other apps, lets you detect which apps are installed.
I wasn't aware of this before but apparently you can also use sysctl() to check the names of running processes (which is less reliable as processes will get bumped off if the foreground app requires more memory).
I wasn't aware of this before but apparently you can also use sysctl() to check the names of running processes (which is less reliable as processes will get bumped off if the foreground app requires more memory).
More here: http://danielamitay.com/blog/2011/2/16/how-to-detect-install...