Determining what other application are in use - objective-c

Question

I was wondering if it is possible to determine within my program what other apps are currently being used by the user. For example, the user might be using Safari and Mail.
From there, I was curious to see if I can determine if the user is actively using the open app. IF the computer is sitting and the user is not using it, I would determine that none of the open apps are currently in use. If a user is actively searching the web, I would determine that Safari is currently being used (or whatever other internet browser).
From there, I was wondering if it is possible to see what the user is doing in the app... well this one is mostly for internet browsers. I want to know which website the user is currently on. If this isn't possible from a normal application, would it be possible to do in a web browser extension?
Thanks for the help!

Answer 1

You can get some hint from "ps" unix command, but not the full answer to your question:
ps aux
Look at the "STAT" column, roughly:
R means running
+ means interactive
Precisely:
state The state is given by a sequence of characters, for example, ``RWNA''. The first character indicates the run state of the process:
I Marks a process that is idle (sleeping for longer than about 20 seconds).
R Marks a runnable process.
S Marks a process that is sleeping for less than about 20 seconds.
T Marks a stopped process.
U Marks a process in uninterruptible wait.
Z Marks a dead process (a ``zombie'').
Additional characters after these, if any, indicate additional state information:
+ The process is in the foreground process group of its control terminal.
< The process has raised CPU scheduling priority.
> The process has specified a soft limit on memory requirements and is currently exceeding that limit; such a process is (necessarily) not swapped.
A the process has asked for random page replacement (VA_ANOM, from vadvise(2), for example, lisp(1) in a garbage collect).
E The process is trying to exit.
L The process has pages locked in core (for example, for raw I/O).
N The process has reduced CPU scheduling priority (see setpriority(2)).
S The process has asked for FIFO page replacement (VA_SEQL, from vadvise(2), for example, a large image processing program using virtual memory to sequentially
address voluminous data).
s The process is a session leader.
V The process is suspended during a vfork(2).
W The process is swapped out.
X The process is being traced or debugged.
From there, you can have a few indication of what the user is using, BUT it doesn't mean he is interacting with it.
False positive: background servers that will do batch heavy processing (they will be in R state).
Another way to look at it is to find which application is being in Foregroud currently.
Try:
osascript -e 'tell application "System Events"' -e 'set frontApp to name of first application process whose frontmost is true' -e 'end tell'
From shell.
You can let it run:
while sleep 5; do osascript -e 'tell application "System Events"' -e 'set frontApp to name of first application process whose frontmost is true' -e 'end tell'; done
And even with this, try it and then press F11 and F12 : you'll see that while on Expose / Dashboard or else, this doesn't get correctly refreshed...
See:
http://alvinalexander.com/mac-os-x/applescript-unix-mac-osx-foreground-application-result