Type Alias AUImplementorStringFromValueCallback 

pub type AUImplementorStringFromValueCallback = *mut DynBlock<dyn Fn(NonNull<AUParameter>, *const AUValue) -> NonNull<NSString>>;

Available on crate features AUAudioUnitImplementation and AUParameters and block2 only.

A block called to convert an AUParameter’s value to a string.

See also Apple’s documentation