Swift4 Xcode9 Passing variable between ViewControllers through segue - segue

Question

class InstanceViewController: NSViewController{
#IBOutlet weak var InstanceAddr:NSTextField!
var input: String = ""
override func viewDidLoad(){
super.viewDidLoad()
}
override func prepare(for segue: NSStoryboardSegue, sender: Any?) {
InstanceViewController().input = "https://google.com"
if (segue.identifier?.rawValue == "moveToLoginWindow"){
let destinationVC = segue.destinationController as! loginWebViewController
destinationVC.address = input
}
}
}
class loginWebViewController: NSViewController{
#IBOutlet weak var instanceview: WKWebView!
var address: String?
override func viewDidLoad(){
var instanceaddress: String? = address
super.viewDidLoad()
var url = URL(string: instanceaddress!)
var request = URLRequest(url: url!)
instanceview.load(request)
}
}
I'm trying to pass variable input: String from InstanceViewController to address: String? in loginWebViewController and load webview with this address. I succeeded loading webview but I can't seem to pass variable through segue moveToLoginWindow. I did everything I could possibly think but nothing worked. Can anyone tell me what I'm doing wrong?

Answer 1

To create a new instance of InstanceViewController inside another instance of the same type makes no sense and causes the issue.
You have to use input of the current instance:
override func prepare(for segue: NSStoryboardSegue, sender: Any?) {
input = "https://google.com"
if segue.identifier?.rawValue == "moveToLoginWindow" {
let destinationVC = segue.destinationController as! loginWebViewController
destinationVC.address = input
}
}
And as the passed type is non-optional declare address also as non-optional
var address = ""

Answer 2

class InstanceViewController: NSViewController{
#IBOutlet weak var InstanceAddr:NSTextField!
var input: String = ""
override func viewDidLoad(){
super.viewDidLoad()
}
override func prepare(for segue: NSStoryboardSegue, sender: Any?) {
InstanceViewController().input = "https://google.com" // Well actually in this line you are creating a new instance for your controller , that will not affect the input value of this controller So correction will be :-
self.input = "https://google.com"
if (segue.identifier?.rawValue == "moveToLoginWindow"){
let destinationVC = segue.destinationController as! loginWebViewController
destinationVC.address = input
}
}
}
class loginWebViewController: NSViewController{
#IBOutlet weak var instanceview: WKWebView!
var address: String?
override func viewDidLoad(){
var instanceaddress: String? = address // there is no need of create extra object as both are optional Prefer guard let instanceaddress = address else { return }
super.viewDidLoad()
var url = URL(string: instanceaddress!)
var request = URLRequest(url: url!)
instanceview.load(request)
}
}
This might help you :-
class InstanceViewController: NSViewController{
#IBOutlet weak var InstanceAddr:NSTextField!
var input: String = ""
override func viewDidLoad(){
super.viewDidLoad()
}
override func prepare(for segue: NSStoryboardSegue, sender: Any?) {
self.input = "https://google.com"
if (segue.identifier?.rawValue == "moveToLoginWindow"){
let destinationVC = segue.destinationController as! loginWebViewController
destinationVC.address = input
}
}
}
class loginWebViewController: NSViewController{
#IBOutlet weak var instanceview: WKWebView!
var address: String?
override func viewDidLoad(){
super.viewDidLoad()
guard let instanceAddress = address, let url = URL(string: instanceAddress) else { return}
var request = URLRequest(url: url)
instanceview.load(request)
}
}