Just want a reminder of the syntax? Jump to the TL;DR. The selector is key to Objective-C’s dynamic runtime nature. It’s just a name that’s used, at runtime, as a key into a dictionary of function pointers. Whenever you send a message to an Objective-C object, you’re actually using a selector to look up a function to call. Sometimes selectors bubble up in Cocoa/CocoaTouch API, and you will need to