imenu parsing of ObjC classes and selectors

I've been working on a bunch of ObjC lately, and for the most part objc-mode (CC-mode v5.35.2) works well for it.  Sometimes, however, I notice imenu fails to parse certain class implementations correctly.  Not sure why.  Here's an example excerpt.   

Here's imenu's listing for this file (from imenu--make-index-alist):

(("NSMutableArray(Emacs)" . 1882) ("-enqueue:" . 1922)
 ("-dequeue" . 2030) ("NSData" . 19) ("NSString" . 200)
 ("NSFont" . 1588) ("NSFont" . 1844))

It has a number of problems:

    • It produces spurious matches for the @end // Class (Category) lines
    • It fails to group methods with class (aka selector in ObjC).  This does work for many cases, not sure why it sometimes fails.
    • It misses entirely the methods under NSData and NSString.
    • When "class method" association does work, sometimes it associates with the prior class in the file (not features in this reproducer).

 Happy to try any tests.  Thanks for the CC-mode family: true workhorses!

JDS