How to Identify if the process in User Interface Process?

How can I get information from a process that it is UI(User Interface) process or non-ui?

With UI process I mean, Finder, Dock, System UI server, or any other mac application which has UI interface and it is used by Window Server.

I want to determine this information from ProcessID.

I am using mac os x.

There is no way to determine based purely on the PID number what a specific process is. The reason for this: Process IDs are assigned (somewhat) sequentially from PID=1 on startup, and startup can be different for different systems. The process ID will also be reassigned if, for example, Finder or Dock crashes and has to be restarted.

If you can run a terminal command with a specific pid that you have, though, do this:

ps -p <pid> -o ucomm=

You'll get the filename of the process, which you can check against a list of ones you know are UI processes. For example, here is the output of certain ps commands on my system for my current login session:

> ps -p 110 -o ucomm=
Dock

> ps -p 112 -o ucomm=
Finder

And the following command will give you a list of processes in order of process ID, with only the name:

> ps -ax -o pid=,ucomm=
   1 launchd
  10 kextd
  11 DirectoryService
     ...

EDIT: You may be able to do what you ask, though it is convoluted. This answer mentions:

The function CGWindowListCopyWindowInfo() from CGWindow.h will return an array of dictionaries, one for each window that matches the criteria you set, including ones in other applications. It only lets you filter by windows above a given window, windows below a given window and 'onscreen' windows, but the dictionary returned includes a process ID for the owning app which you can use to match up window to app.

If you can obtain all the CGWindows and their respective pids, then you will know the pids of all UI applications without needing to run ps at all.

Rahul has implemented the following code for this approach, which he requested I add to my answer:

CFArrayRef UiProcesses()
{
    CFArrayRef  orderedwindows = CGWindowListCopyWindowInfo(kCGWindowListOptionAll, kCGNullWindowID);
    CFIndex count = CFArrayGetCount (orderedwindows);
    CFMutableArrayRef uiProcess = CFArrayCreateMutable (kCFAllocatorDefault , count,  &kCFTypeArrayCallBacks);
    for (CFIndex i = 0; i < count; i++)
    {
        if (orderedwindows)
        {
            CFDictionaryRef windowsdescription = (CFDictionaryRef)CFArrayGetValueAtIndex(orderedwindows, i);
            CFNumberRef windowownerpid  = (CFNumberRef)CFDictionaryGetValue (windowsdescription, CFSTR("kCGWindowOwnerPID"));
            CFArrayAppendValue (uiProcess, windowownerpid);

        }
    }
    return uiProcess;
}

Kind of resurrecting this one... But for macOS, to get the process ids of various elements of the UI, you can use lsappinfo since maybe Tiger? The manpage says April, 2013, but I think it was around at the time of this question being asked and probably earlier. The command should be run as the user who currently owns the loginwindow process.

lsappinfo info -only pid Dock
"pid"=545

Try the following.

#include <unistd.h>

  if (isatty(STDIN_FILENO) || isatty(STDOUT_FILENO) || isatty(STDERR_FILENO))
    // Process associated with a terminal
  else
    // No terminal - probably UI process

On the lines of darvidsOn, below is the answer to your question.

  CFArrayRef UiProcesses()
    {
        CFArrayRef  orderedwindows = CGWindowListCopyWindowInfo(kCGWindowListOptionAll, kCGNullWindowID);
        CFIndex count = CFArrayGetCount (orderedwindows);
        CFMutableArrayRef uiProcess = CFArrayCreateMutable (kCFAllocatorDefault , count,  &kCFTypeArrayCallBacks);
        for (CFIndex i = 0; i < count; i++)
        {
            if (orderedwindows)
            {
                CFDictionaryRef windowsdescription = (CFDictionaryRef)CFArrayGetValueAtIndex(orderedwindows, i);
                CFNumberRef windowownerpid  = (CFNumberRef)CFDictionaryGetValue (windowsdescription, CFSTR("kCGWindowOwnerPID"));
                CFArrayAppendValue (uiProcess, windowownerpid);

            }
        }
        return uiProcess;
    }

Just compare the processid you have against the array items to get the desired result.