How do I identify files being used by active application?

Question

I have been tasked with identifying the file names or file title that are associated with a macOS app that is being used by the user. I have found out that using NSWorkspace.shared.frontmostApplication?.localizedName works for identifying the active application. I have been unable to find out how to identify the name of the open file names associated with the application. For example, Google Chrome is my currently active application. "How do I identify files being used by active application? Stack Overflow" is the file name. How do I detect that on my macOS app?

Thanks for any help!

Answer 1

This is Unix. Use the tools that Unix gives you.

So in this instance, you might get the pid for this process and use lsof. For example:

$ ps -u mattmobile | grep "TextEdit"
  501 13602 ??         0:01.48 /System/Applications/TextEdit.app/Contents/MacOS/TextEdit

So now we know that TextEdit is 13602. Well then:

$ mattmobile:~ mattmobile$ lsof -p 13602
COMMAND    PID       USER   FD     TYPE DEVICE  SIZE/OFF                NODE NAME
TextEdit 13602 mattmobile  cwd      DIR    1,4       384         12884936974 /Users/mattmobile/Library/Containers/com.apple.TextEdit/Data
TextEdit 13602 mattmobile  txt      REG    1,4    399856 1152921500311959473 /System/Applications/TextEdit.app/Contents/MacOS/TextEdit
... and so on ...