This question is very similar to Xcode debugger reporting Swift dictionaries as empty (po reports {}) but differs in that I'm not relying on the "po" command, but rather on the default display of the debugger. Also, I'm experiencing this on both the iPad 2 simulator and on an iPad mini 1st gen device.
Using Swift with Xcode 6.3.2.
As you can see, calling count on the dictionary (called "simultaneousSoundPlayers") returns 1 (which I believe to be correct at this point, since at this point an NSLog command also displays a count of 1).
But the debugger's inspection of the dictionary itself (either by standalone name or expanding the parent object, self) makes the dictionary appear to have no key/value pairs.
Any idea why this happens? Is it just debugger quirkiness?