Objective-C built the iPhone app gold rush, and its square-bracket message syntax is unlike anything else on this site. A screen of it suggests a veteran iOS developer maintaining an app old enough to vote — or at least old enough to predate Swift.
The sample defines a photo-gallery data source with formal @protocol declarations on Foundation and UIKit, in proper pre-Swift style. The nostalgia is fully functional; the code is not.
Like every HackerTyping screen, this is harmless entertainment: the Objective-C code is a local, prewritten sample that is displayed and never executed, and your keystrokes are never recorded. See the main hacker typer, the filmmaker guide for shooting tips, or the privacy policy. A project of Wild Monkey Labs.