In an class header I have seen something like this:

enum {
    kAudioSessionProperty_PreferredHardwareSampleRate           = 'hwsr',   // Float64
    kAudioSessionProperty_PreferredHardwareIOBufferDuration     = 'iobd'   // Float32
};

Now I wonder what data type such an kAudioSessionProperty_PreferredHardwareSampleRate actually is?

I mean this looks like plain old C, but in Objective-C I would write @"hwsr" if I wanted to make it a string.

I want to pass such an "constant" or "enum thing" as argument to an method.