The NSScreen screen property is nullable. From the docs for NSWindow screen:
"The value of this property is the screen where most of the window is on; it is
nil when the window is offscreen."
I would go with Steve’s suggestion as much as possible, The NSScreen class has
the info you need.
Jack
> On Nov 17, 2022, at 10:44 AM, Gabriel Zachmann via Cocoa-dev
> <cocoa-dev@lists.apple.com> wrote:
>
> In my screensaver (macOS),
> I am trying to retrieve the 'screen number' (NSScreenNumber) for the screen
> on which I am running.
>
> So, in
> - (void) viewWillMoveToWindow: (NSWindow *) newWindow
> I have this line of code:
> displayID_ = [ [[newWindow screen] deviceDescription] objectForKey:
> @"NSScreenNumber"];
>
> This sometimes works (I get the correct screen number),
> and sometimes it does not, i.e., I get displayID_ = nil!
> (Usually after invoking some other screen savers in System Preferences.)
>
> I don't see a pattern.
>
> Curiously, these lines in viewWillMoveToWindow always work:
>
> for ( NSScreen * s in [NSScreen screens] )
> {
> NSDictionary<NSDeviceDescriptionKey, id> * device_description = [s
> deviceDescription];
> NSNumber * n = [device_description objectForKey: @"NSScreenNumber"];
> [...]
> }
>
> I always get non-null and correct 'screen numbers' n.
>
>
> So, I am wondering, why does the first line sometimes NOT work?
> And what is the proper way to retrieve the screen number on which my screen
> saver is running?
> Should I use [NSScreen mainScreen] ?
>
> Please note, that there might be several monitors attached to the Mac!
> (Some users have up to 6)
>
> Thanks a lot in advance.
>
> Best regards, Gabriel
>
> _______________________________________________
>
> Cocoa-dev mailing list (Cocoa-dev@lists.apple.com)
>
> Please do not post admin requests or moderator comments to the list.
> Contact the moderators at cocoa-dev-admins(at)lists.apple.com
>
> Help/Unsubscribe/Update your Subscription:
> https://lists.apple.com/mailman/options/cocoa-dev/jackbrindle%40me.com
>
> This email sent to jackbrin...@me.com
_______________________________________________
Cocoa-dev mailing list (Cocoa-dev@lists.apple.com)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com
This email sent to arch...@mail-archive.com
