Swift: A function with a Selector argument returns an unmanaged<AnyObject>?

Question

What is the use of -

func perform(_ aSelector: Selector!) -> unmanaged<AnyObject>!

in iOS?

• To call a method of a class?
• To add a selector method?
• To add a class delegate?
• To define a class? (I doubt it's this)

I was originally thinking that it it was to add a selector method, but after looking at it some more I think it may be "to call a method of a class." Selectors are used for target/action paradigms where I kick something off and when the event fires or finishes then it wants to fire off some kind of action method. In this example do I pass it a parameter of a selector function then at the end of this "perform" function, I am returning an unmanaged object of any type? Does that even make sense?

Thanks!

Answer 1

In Swift this is basically useless. It's bridged from Objective-C, where it used to be very useful (before ARC), but now it's a bit tricky.

The point of it is to send a message by name and get a result. Generally speaking that translates to calling a method of that name.