Nibs and storyboards are full of this stuff. They instantiate classes by name, call methods by name, etc. Some example documentation if you're curious:

https://developer.apple.com/library/content/documentation/Ge...

https://developer.apple.com/library/content/documentation/Co...

https://developer.apple.com/library/content/documentation/Co...

Objective-C's dispatch is built around looking up methods by their selector, which is effectively an interned name. Looking up the selector can be slow, but once you have one, invoking a method using a dynamic selector is as fast as invoking one with a selector that's known at compile time.