I found a video from last year's WWDC which included scripts to do this. At least I'm in now and can do some debugging.

Filed as FB9120139. Will be submitting a TSI.

So far, I've tried the video from WWDC 2020 and the new video from WWDC 2021. Nothing works. It appears to read the kernel ok for CIFilter, but won't even do that when declared as a CIColorFilter (a la WWDC 2020). I'm also confused as the whether the samplers (three) should be passed to the kernel or pass the samples instead. Previously, without Metal, I passed the samplers. (That was the version that used to work, but then didn't.) My MBP is now 7 yrs old, but supposedly should still work. (Waiting anxiously for the new MBP to release.)

TSI 769573020 was filed and charged to my account on May 27. So far, Apple has been totally non-responsive. Nada. I would at least expect an acknowledgment.

Doesn't Work.

Well I'm back, and this bug has never been fixed in Objective C, and I'm pretty sure it also persists in Swift. The problem is that clickedPathItem is readonly and returns a reference to the clicked item, but pathItems is "copy" and does not contain the clicked item. Copies likely also copy the enclosed secretCells. Both indexOfObject: and indexOfObjectIdenticalTo: return NSNotFound and are therefore useless. While I could try to find the index by comparing titles, that is also useless because URL paths can contain multiple titles that are identical. So far, I have not come up with a workaround. I'm trying to get rid of compiler complaints about using deprecated cells.

Yes. Path titles for files may not be unique, so that is a problem. I've been bitching about NSPathControl for several years and recently filed another bug report which has not even been acknowledged. This thing has never worked with "items", but they refuse to do anything about it, so I'm still using cells, which do work. ClickedPathItem will never return an item in the items array. Also, I need the geometry of each cell, which I use for hover popovers, and you cannot obtain that using items.