Swift 如何在应用程序启动时显示警报

我想在当天我的应用程序首次启动时发出警报。 我认为这样做的地方是appDelegate（如果我错了，请纠正我）。我有两个问题，一个是：我不知道该函数应该驻留在appDelegate中的哪个函数下（目前只选择了func应用程序），第二个是：我不知道如何向打开的视图显示alertController。到目前为止，我已经做到了这一点

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

    if checkIfNewDay() {
        let alert = UIAlertController("some title": alertTitle, message: "some message", preferredStyle: .Alert)
        alert.addAction(UIAlertAction(title: "Okay", style: .Cancel, handler: nil))

        // What to do here????
    }

---

我应该用什么代码替换注释？

尝试使用此方法：

applicationdibecomeactive

func applicationDidBecomeActive(application: UIApplication) {
     //This method is called when the rootViewController is set and the view.
    if checkIfNewDay() {
       let alert = UIAlertController("some title": alertTitle, message: "some message", preferredStyle: .Alert)
       alert.addAction(UIAlertAction(title: "Okay", style: .Cancel, handler: nil))
       self.window?.rootViewController?.presentViewController(alert, animated: true, completion: nil)
    }
}

---

尝试使用此方法：

applicationIDBecomeActive

func applicationDidBecomeActive(application: UIApplication) {
     //This method is called when the rootViewController is set and the view.
    if checkIfNewDay() {
       let alert = UIAlertController("some title": alertTitle, message: "some message", preferredStyle: .Alert)
       alert.addAction(UIAlertAction(title: "Okay", style: .Cancel, handler: nil))
       self.window?.rootViewController?.presentViewController(alert, animated: true, completion: nil)
    }
}