Use delegate in Swift

protocol

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protocol ControllerDelegate : NSObjectProtocol {
    func Controller(Controller: obj, clickedIndex index: Int);
}

The variable for delegate

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class Controller: UIView {
    var delegate:ControllerDelegate!;
    ...

call delegate function like this

Now you donot need to point a function like @selector("function:name:")
Using respondsToSelector("function:name:") is OK

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func buttonClicked(sender:UIButton) {
    if self.delegate.respondsToSelector("Controller:clickedIndex:") {
        delegate.Controller(self, clickedIndex:sender.tag);
    }
}