Type Alias dispatch_data_applier_t 

pub type dispatch_data_applier_t = *mut DynBlock<dyn Fn(NonNull<DispatchData>, usize, NonNull<c_void>, usize) -> bool>;

A block to be invoked for every contiguous memory region in a data object.

Parameter region: A data object representing the current region.

Parameter offset: The logical offset of the current region to the start of the data object.

Parameter buffer: The location of the memory for the current region.

Parameter size: The size of the memory for the current region.

Returns: A Boolean indicating whether traversal should continue.

See also Apple’s documentation