Updating label in view using VIPER architecture

Question

I am new to VIPER and I have build the most simplest demo in that architecture, but I have trouble, as UILabel in View/View Controller is not updated. This is the relevant code: View:

    override func viewDidLoad() {
    super.viewDidLoad()
    presenter?.updateView()
}

Presenter:

func updateView() {
    interactor?.getText()
}

Interactor:

    func getText() {
    presenter?.gotText(text: "Hello Viper")
}

Presenter:

    func gotText(text: String) {
    view?.updateLabel(text: text)
}

View:

func updateLabel (text: String) {
    print(text)
        helloLabel.text = text
}

print(text) returns the value, but the view itself is not updated.

I tried with updating on the main thread, but with no luck. I have seen some project s with the similar pattern (Updating a view in ViewController /label/backgroundColor etc), but I can't figure out what is wrong with my code.

The sample is available at GitHub https://github.com/veliborsantic/VIPER-simple-example The similar project is available at https://github.com/smalam119/live-news-viper, which runs as expected.

EDIT 1: I realized that viewDidLoad func is called twice. I set print messages in both viewDidLoad() and updateLabel (text: String) as follows:

override func viewDidLoad() {
     super.viewDidLoad()
     print("viewDidLoad: ", helloLabel.text!)
     presenter?.updateView()
}

func updateLabel (text: String) {
     helloLabel.text = text
     print("updateLabel: ", helloLabel.text!)
}

Outputs:
viewDidLoad:
updateLabel: Hello Viper
viewDidLoad:

If I remove configuration for initialViewController in AppDelegate, viewDidLoad is called once, but the module is not loaded.

EDIT 2 / SOLVED After researching, I had to make 3 things: Tell that I do not want initializing controller via storyboard, so: 1. Turn off "is Initial View Controller" 2. Deattach Main in Deployment Info and 3. All code from AppDelegate move to Scene Delegate in func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions)

Can you please show your Wireframe or the way to assemble all the layer of the Viper module — Luis Mejías

FindYourBalance FindYourBalance · Accepted Answer · 2019-12-01T19:31:19

Just try view.layoutIfNeeded() after setting text

Updating label in view using VIPER architecture

1 Answers