Passing data from model to controller - ios

Question

I am wondering what would be the best practice when I want to pass data from model to controller.
What I want to do
I would like to update a label when the time changes.
CurrentTime.swift (Model)
var timer: Timer?
var currentTime: String?
init() {
if timer == nil{
timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(updateCurrentTime), userInfo: nil, repeats: true)
}
}
#objc private func updateCurrentTime(){
let df = DateFormatter()
df.dateFormat = "HH:mm"
df.timeZone = TimeZone.current
let timezoneDate = df.string(from: Date())
currentTime = timezoneDate
}
ViewController.swift
class ViewController: UIViewController {
#IBOutlet var timeLabel: UILabel!
var currentTime = CurrentTime()
override func viewDidLoad() {
}
#IBAction func closeBtnWasPressed(_ sender: UIButton) {
dismiss(animated: true, completion: nil)
}
}

Answer 1

Option 1
1- Add this var
weak var delegate: ViewController?
2- in viewDidLoad of the vc
currentTime.delegate = self
3-
let timezoneDate = df.string(from: Date())
currentTime = timezoneDate
delegate?.update(currentTime)
4- inside the vc
func update(_ data:String) {
lbl.text = data
}
off course you can do
delegate?.lbl.text = currentTime
but above is MVC
Option 2
var ob:NSKeyValueObservation!
and in viewDidLoad
ob = currentTime.observe(\CurrentTime.currentTime, options: .new) { cur, tex in
timeLabel.text = tex
}

Answer 2

You should define a Dynamic class like this:
class Dynamic<T> {
var bind: (T) -> Void = { _ in }
var value: T? {
didSet {
bind(value!)
}
}
init(_ v: T) {
value = v
}
}
In your model change definition of the currentTime property like this:
var currentTime: Dynamic<String>
In your controller in viewDidLoad method add these codes:
yourModel.currentTime.bind = { [weak self] time in
self?.timeLabel.text = time
}