Type Alias AVAudioNodeCompletionHandler 

pub type AVAudioNodeCompletionHandler = *mut DynBlock<dyn Fn()>;

Available on crate features AVAudioTypes and block2 only.

Generic callback handler.

Various AVAudioEngine objects issue callbacks to generic blocks of this type. In general the callback arrives on a non-main thread and it is the client’s responsibility to handle it in a thread-safe manner.

See also Apple’s documentation