macOS Look at the Objects of A Running Application?

I have started learning Cocoa and I have a question. In an application I am trying it has to get information from other applications, ones that I have not made and do not have the source for. Specifically how can I have an application look at what objects another application has created.

For Example: My application wants to find the value of a slider in another application.
How can I "ask" that other applications slider what its value is? I know how to ask a slider that is part of my own application, so that isn't a problem.

Short Version: Can I see what objects another application has created and talk to them?

Is this possible? Thanks

Thanks for the replies. F-Script does exactly what I want, only now I have to figure out how to make F-Script Anywhere integrate into my application, so that I can get the value of stuff from the app it is inserted into, and create a pointer to it. Maybe I could create a pointer to the location of it, but I don't know yet.

Actually, does anyone know if you can use the accessibility framework to find out the value of a progress bar? That seems to be the easiest way now.