如何将const void *字节传递给Swift的Objective-C块?

I'm writing some Swift (1.2) code that calls an Objective-C library (transcribing some earlier Objective-C code). It's not clear how it's supposed to work. I've tried a bunch of variations, and nothing satisfies the compiler. Here's the Objective-C code I started with:I'm writing some Swift (1.2) code that calls an