What is the @objcMembers attribute?

Swift version: 5.4

Paul Hudson @twostraws May 28th 2019

By default Swift generates code that is only available to other Swift code, but if you need to interact with the Objective-C runtime – all of UIKit, for example – you need to tell Swift what to do.

If you just want to expose a single method or property, you can mark that method using the @objc attribute. However, if you want all methods in a class to be exposed to Objective-C you can use a shortcut: the @objcMembers keyword:

@objcMembers class MyController: UIViewController {
    func login() {

    }
}

In that code, the login() method will automatically be exposed to Objective-C in the same way as if it had been marked with @objc, because the whole class it’s inside is marked with @objcMembers.