Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
994 views
in Technique[技术] by (71.8m points)

swift ios - How to run function in ViewController from AppDelegate

I am trying to run a function in certain ViewController using AppDelegate

func applicationDidBecomeActive(_ application: UIApplication) {
        ViewController().grabData()
}

But somehow the function does not seem to run at all when the app has become active after entering the app from the background.

The function looks like this

func grabData() {
        self._DATASERVICE_GET_STATS(completion: { (int) -> () in
            if int == 0 {
                print("Nothing")
            } else {
                print(int)

                for (_, data) in self.userDataArray.enumerated() {
                    let number = Double(data["wage"]!)
                    let x = number!/3600
                    let z = Double(x * Double(int))
                    self.money += z
                    let y = Double(round(1000*self.money)/1000)

                    self.checkInButtonLabel.text = "(y) KR"
                }

                self.startCounting()
                self.workingStatus = 1
            }
        })
    }

And uses this var

var money: Double = 0.000

What have I missed?

Thanks!

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

ViewController().grabData() will create a new instance of the ViewController and call this function. Then.. as the view controller is not in use it will be garbage collected/removed from memory. You need to be calling this method on the actual view controller that is in use. Not a new instance of it.

The best option would be to listen for the UIApplicationDidBecomeActive notification that iOS provides.

NotificationCenter.default.addObserver(
    self,
    selector: #selector(grabData),
    name: NSNotification.Name.UIApplicationDidBecomeActive,
    object: nil)

make sure that you also remove the observer, this is usually done in a deinit method

deinit() {
    NotificationCenter.default.removeObserver(self)
} 

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

2.1m questions

2.1m answers

60 comments

57.0k users

...