Swift NSUserNotificationCenter didActivateNotification无法正常工作

我正在开发一个快速的OS X应用程序，但在理解userNoticiation / didActivateNotification结构时遇到了麻烦。我已经查看了文档并进行了搜索，但仍然无法解决。对于以下代码的任何指导将不胜感激：

func notify(message: String, callBack: String) {


    println(message)
    println(callBack)
    var notification:NSUserNotification = NSUserNotification()
    notification.title = "New Phone Call"
    notification.informativeText = message
    notification.actionButtonTitle = "Lookup"
    notification.hasActionButton = true
    var center:NSUserNotificationCenter = NSUserNotificationCenter.defaultUserNotificationCenter()


    center.delegate = self
    center.scheduleNotification(notification)



}
func notify (center: NSUserNotificationCenter, didActivateNotification notification: NSUserNotification){
    center.delegate = self
    println("clicked")  //this does not print
}

通知将完全按照我的意愿显示。单击我已定义的“查找”按钮，将使应用程序在首次单击时进入前台，但是我希望处理该操作的代码不会触发。

提前致谢。