Chilkat v9.3.0 for Cocoa now includes the asynchronous functionality and event callback functionality that has been available in the C++ libs.
Asynchronous methods run in a background thread such that the call immediately returns to the application. Events are not fired w/ asynchronous method calls — your app would periodically check to see if the background task is finished.
To implement an event callback, your app would define/implement a class that inherits from one of the Cko*Progress base classes. You provide method implementations to override the methods specified in the Cko*Progress classes (see the header files). The callback object is specified via the EventCallbackObject property. For example:
// property setter: EventCallbackObject
– (void)setEventCallbackObject: (CkoFtp2Progress *)eventObj;