set volume not working in xcode with applescript cocoa objc

Question

I have an applescript xcode project in xcode 3.2 and am trying to change the system volume...however it doesn't work...it either stops the nstimer or doesnt do anything at all...

Is there a way to log the errors so that I can pinpoint the issue?

Here is my code

set newVolume to 50
set volume output volume newVolume
textName's setStringValue_(currentVolume)
set currentVolume to newVolume

obv this is a much more condense version but this literally does not work...it is inside of an NSTimer but, even when not within an NSTimer it still does not work...newVolume, currentVolume, and textName are all declared...do I need to declare something for the set volume line?

Answer 1

So, your actual question was simply how to log errors from AppleScriptObjC:

AppleScriptObjC will log any errors thrown in your script to the console -- just look in the bottom pane in Xcode. For instance, in your case you should see something like “«script» doesn’t understand the «aevtstvl» message.” (This isn’t terribly clear, but it’s telling you that your script sent a set volume command to a script object, which didn’t have a handler for it.) If you want to capture and log errors yourself, you can put troublesome sections inside a try/on error block, and deal with it yourself in the error handler.

If you’re feeling extra inquisitive, you can also turn on the NSScriptingDebugLogLevel preference, like this:

defaults write com.me.myapp NSScriptingDebugLogLevel 1

...and AppleScriptObjC will log information about every message sent either way across the bridge. (Set it to 0 or use defaults delete to turn it off.)

That’s error logging. Now, what you didn’t actually ask, but I’m going to answer anyway, was “How do I fix my set volume command?”

Short version: add tell current application to:

tell current application to set volume output volume 50

And yes, the range for the “new” volume parameters is 0 to 100. The old compatibility one goes from 0 to 7. (Why? The old Control Panel volume slider had 8 stops.)

Long version:

There’s a bad interaction between the default direct parameter and set volume’s handling of it. When using AppleScriptObjC, “it”, and therefore the default direct parameter, unless you say otherwise, is the current script, and set volume chokes on that. You can force “it” to be nothing by saying tell current application to. (Alternatively, you could give it an explicit direct parameter by using the old-fashioned form set volume x where x is a real number from 0 to 7. However, this doesn’t match the numbers you get from get volume settings, only lets you set the output volume, and doesn’t let you set things like “muted” correctly.)

And by the way, if your AppleScriptObjC project is sufficiently simple (in particular, if you don’t need any interface), you can write it directly in AppleScript Editor: choose File > New from Template > Cocoa-AppleScript Applet, and use the normal AppleScript on run and on open handlers, except that you can now also invoke anything from Cocoa.