Categories
ios selector swift

Swift access control with target selectors

Have a look at this example code:

class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let letterButton = UIButton.buttonWithType(.Custom) as UIButton
self.view.addSubview(letterButton)
letterButton.addTarget(self, action:Selector("buttonDidTap:"), forControlEvents: .TouchUpInside)
}
func buttonDidTap(button: UIButton!) {
print(button.char)
}
}

The target action for the UIButton works fine as long as Selector is public or internal, but if it’s private, it crashes due to unrecognized selector sent to instance

Is there any way I can achieve this ? I don’t want to make tap function public or internal.

you need @objc to expose a private method to objc runtime

@objc private func buttonDidTap(button:UIButton!) {
println(button.char)
}

From Xcode6 beta4 release notes

Declarations marked private are not exposed to the Objective-C runtime
if not otherwise annotated. IB outlets, IB actions, and Core Data
managed properties remain exposed to Objective-C whatever their access
level. If you need a private method or property to be callable from
Objective-C (such as for an older API that uses a selector-based
callback), add the @objc attribute to the declaration explicitly.! !