从2个View Controller传递数据而没有segue

Question

I have a mainviewcontroller and a popup view controller which opens without a segue.

the popup viewcontroller recive data from Firebase, and then i need to append this data to an array in the mainviewcontroller.

How can i do that?

(i tried to create a property of the popupviewcontroller in the mainviewcontroller, but in crashes the app)

this is the code that opens the popup:

 @IBAction func showPopUp(_ sender: Any) {
        let popOverVC = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "sbPopUp") as! PopUpViewController
        self.addChild(popOverVC)
        popOverVC.view.frame = self.view.frame
        self.view.addSubview(popOverVC.view)
        popOverVC.didMove(toParent: self)

Answer 1

You need to connect the classes so that the popup class knows what to do with the data once it has been received. Here's a sample structure that works in a playground that you should be able to apply to your real classes.

class MainClass {

    func showPopUp() {
        let popOverVC = PopUpClass()
        popOverVC.update = addToArray
        popOverVC.receivedData()
    }

    func addToArray() {
        print("Adding")
    }
}

class PopUpClass {
    var update: (()->())?

    func receivedData() {
        if let updateFunction = update {
            updateFunction()
        }
    }
}

let main = MainClass()
main.showPopUp()

Answer 2

Or you could create a global variable so it can be accessed anywhere. ... It is better to pass data but I just thought it would be easier in this instance, so the variable can be accessed anywhere in your entire project.

Answer 3

if it is just a notification, you can show it in an alert, but if you don't want to use an alert my offer to present another view controller is not like this , try my code :

//if you have navigation controller ->
let vc = self.storyboard?.instantiateViewController(
            withIdentifier: "storyboadrID") as! yourViewController
        self.navigationController?.pushViewController(vc, animated: true)
//if you don't use navigation controller ->
let VC1 = self.storyboard!.instantiateViewController(withIdentifier: "storyboadrID") as! yourViewController
            self.present(VC1, animated:true, completion: nil)

also if you want to pass any data or parameter to destination view controller you can put it like this before presenting your view controller :

VC1.textView.text = "test"