How can I call a function that creates a button from another viewcontroller? - swift

Question

I have a function in my TuesdayViewController.swift that creates a button.
Whenever it's Tuesday, I want that button to appear in my ViewController.swift
I have this function in my TuesdayViewController:
func tuesdayView(){
let button = UIButton(frame: CGRect(x: 16, y: 200, width: 343, height: 45))
button.backgroundColor = .red
button.setTitle("Test button", for: .normal)
self.view.addSubview(button)
}
If I call this function in Tuesday's viewDidLoad(), the button shows in the TuesdayViewController.
How can I make it so I call this function through my main ViewController and for the button to show in the main ViewController screen?
I have tried this in my main ViewController but the button doesn't appear:
override func viewDidLoad(){
super.viewDidLoad()
TuesdayViewController().tuesdayVew()
}
Any help would be appreciated!

Answer 1

If I understand your question right, you just want to add the same kind of button from your TuesdayViewController into your MainViewController, and not adding the button to the TuesdayViewController by calling it in the MainViewController.
To do that, you just can declare your tuesdayView as a public property of your TuesdayViewController, like so:
TuesdayViewController.swift
class TuesdayViewController: UIViewController {
public lazy var tuesdayView: UIButton = {
let button = UIButton(frame: CGRect(x: 16, y: 200, width: 343, height: 45))
button.backgroundColor = .red
button.setTitle("Test button", for: .normal)
return button
}()
override func viewDidLoad(){
super.viewDidLoad()
self.view.addSubview(self.tuesdayView)
}
}
And call that property like what you've been doing before.
MainViewController.swift
class MainViewController: UIViewController {
override func viewDidLoad(){
super.viewDidLoad()
let button = TuesdayViewController().tuesdayView
self.view.addSubview(button)
}
}

Answer 2

You need to use an observer with NotificationCenter:
First you need to create a Notification Name
extension Notification.Name {
static let notName = Notification.Name("notName")
}
TuesdayViewController:
override func viewDidLoad() {
NotificationCenter.default.addObserver(self, selector: #selector(tuesdayViewObserver), name: .notName, object: nil)
}
#objc func tuesdayViewObserver(_ notification: Notification) {
//Here you call the tuesdayView function
tuesdayView()
}
And in the controller in which you want to fire the method, you post the notification and the method will be executed:
override func viewDidLoad() {
super.viewDidLoad()
NotificationCenter.default.post(name: .notName, object: nil)
}
For further info, I recommend you to take a look to NotificationCenter and how it works. LINK