macos - OSX Lion AppleScript : How to get current space # from mission control?

Question

I'm trying to figure out how to get the current space # from mission control. Source would be helpful, but more helpful would be info on how to figure this out myself. I've written a few applescripts, but more often than not it seems like any time I need to do something new (that I can't find dictionary documentation for) it falls under the category of "tell this specific app (e.g. "System Events") this very specific thing" and I've no clue how I would actually figure that out.

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Specifically what I am trying to do:

I hate the new mission control in OSX 10.7. I want my spaces "grid" back since I used it all the time. I used to navigate between spaces using arrow keys (e.g. ALT+↑) every few seconds. Now I'm stuck with this clunky 1x9 array of spaces instead of an elegant 3x3 grid. I've re-mapped all my spaces to use the number pad, which partially takes care of the problem (since it is a 3x3 grid), but only when I have an external keyboard attached.

Basically, I want to be able to use ALT+↑ and ↓ again, but to do so I need to detect the current space # so that I can switch from space 5-->2, for example.

Dave's answer below, although far more detailed than I expected, requires writing an app to do this (plus it still doesn't fully answer the question). If it's at all possible, I'd rather just bind a few keys to an applescript.

Answer 1

I'm trying to figure this out myself. Not there yet, but in the right direction:

• Each Mission Control "space" gets a uuid assigned to it...
• ...except for the very first one (AFAIK), and the Dashboard one.

You can read them here:

$ defaults read com.apple.spaces
$ defaults read com.apple.desktop

File locations:

~/Library/Preferences/com.apple.spaces.plist
~/Library/Preferences/com.apple.desktop.plist

Here's mine. I have four spaces enabled, and three entries show up:

$ defaults read com.apple.spaces
{
    spaces =     (
                {
            type = 0; 
            uuid = "9F552977-3DB0-43E5-8753-E45AC4C61973";
        },
                {
            type = 0;
            uuid = "44C8072A-7DC9-4E83-94DD-BDEAF333C924";
        },
                {
            type = 0;
            uuid = "6FADBDFE-4CE8-4FC9-B535-40D7CC3C4C58";
        }
    );
}

If you delete a space, that entry will get removed from the file. If you add a space, an entry will be added. Again, there's never an entry for Desktop 1 or Dashboard.

I'm not sure if there's a public API to figure out what space uuid is being displayed on a display. I'd assume that no uuid means Display 1, and the others' mean Display 1+n.

I took a quick glance through the AppleScript Editor Library (Window ---> Library) and didn't see any entries under System Events for spaces. This is probably something that can be done with Cocoa, perhaps via private API, but I'm not sure about AppleScript.

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UPDATE - July 23, 2011

It looks like Dock controls Mission Control. You can grab its header files like so:

1. Go to: /System/Library/CoreServices/Dock
2. Right-Click and Show Package Contents
3. Navigate: /Contents/MacOS/
4. Copy and paste the Dock binary to your desktop.
5. Run: $class-dump ~/Desktop/Dock

That'll spit out all of its header files (it's long; almost 7,500 lines). You can see the spaceUUID strings appearing in there. There's a class called WVSpace which appears to represent a single Space in Mission Control, and a lot of other WV* classes.

I'll keep looking at it tomorrow; too tired now. :)

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UPDATE - July 24, 2011

Inside Dock there's a class called WVSpaces. It has a number of attributes including:

WVSpace *currentSpace;
unsigned int currentWorkspace;
WVSpace *nextSpace;                     // Space on the right???
WVSpace *previousSpace;                 // Space on the left???
BOOL currentSpaceIsDashboard;
BOOL dashboardIsCurrent;
...lots more...

Each WVSpace class has an NSString *_uuid; attribute, which is likely its SpaceUUID. So theoretically you can get the current space number like so:

WVSpace *currentSpace = [[WVSpaces sharedInstance] currentSpace];
NSString *currentSpaceUUID = [currentSpace _uuid];     // Empty string if main space???

The trick is, how to get access to the private WVSpaces class buried inside of Dock? I'm assuming it's Singleton as it has an NSMutableArray *_spaces; attribute, probably with every space listed in it. Only one space gets displayed at a time (this holds true if you're using multiple monitors; the space spans across both of them), so it makes sense to only have one WVSpaces instance.

So it looks like it'll require some SIMBL hacking of Dock to gain access to WVSpaces.