Getting Spaces and their order for each display

watch_spaces.swift

var observer: Observer!
func stuff() {
    guard let database = UserDefaults.init(suiteName: "com.apple.spaces") else {
        fatalError("cannot read spaces data")
    }
    print(String(describing: database.object(forKey: "SpacesDisplayConfiguration")))
    observer = Observer(object: database)
}

class Observer: NSObject {
    @objc var database: UserDefaults
    var observation: NSKeyValueObservation?

    init(object: UserDefaults) {
        database = object
        super.init()

        database.addObserver(self, forKeyPath: "SpacesDisplayConfiguration", options: [.new, .old,
            .initial], context: nil);
    }

    override func observeValue(forKeyPath: String?, of object: Any?, change: [NSKeyValueChangeKey:
        Any]?, context: UnsafeMutableRawPointer?) {
        print("changed")
    }
}

This also includes a list of window numbers for each space, but it is not updated when windows are moved between spaces or the user changes spaces. It only updates because the space configuration changed (spaces were added, removed, or reordered).

The idea (except KVO) comes from this blog post: http://ianyh.com/blog/identifying-spaces-in-mac-os-x/

Do you know if the "app-bindings key updates its values when a user right-clicks on an application's Dock icon and changes the "Assign to" options?

For example, does changing options from None to All Desktops update the app-Bindings values?

Off the top of my head I don't know, but it seems plausible that it would.

Mostly I've just had to experiment with little programs and find out what happens. (Which isn't great for backwards/forwards compatibility, but not much else you can do.)