ios - Referring to self during property declaration in Swift

Question

I'm trying to declare and initialize a property with the following code.

class ClassName: UIViewController {

　　private let doneButtonItem = UIBarButtonItem(title: "Done", style:　UIBarButtonItemStyle.Plain, target: self, action: "doneButtonDidTapped")

   func doneButtonDidTapped() {
      println("Ulala!")
   }
}

However, I got the following error.

Cannot find an initializer for type 'UIBarButtonItem' that accepts an argument list of type '(title: String, style: UIBarButtonItemStyle, target: ClassName -> () -> ClassName, action: String)'

Anybody know what's going on here? Should I give up my attempts to initialize the property inline with the declaration and do the initialization on init() method instead?

Answer 1

As @giorashc says due to swift's 2-phase initialization, self is not yet initalized so you cannot do it.

But I think you could create a lazy inialization:

lazy private var doneButtonItem : UIBarButtonItem = {
    [unowned self] in
    return UIBarButtonItem(title: "Done", style:UIBarButtonItemStyle.Plain, target: self, action: "doneButtonDidTapped")
    }()