Swift access helper function view - swift

Question

I try to access the function "addNavBar()" from, my helper class, but when I run the emulator, no view is shown on HomeViewController.
Swift 4
HomeViewController.swift
class HomeController: UIViewController {
let NavBar = NavigationBarHelper()
override func viewDidLoad() {
super.viewDidLoad()
NavBar.addNavBar()
}
}
NavigationBarHelper.swift
class NavigationBarHelper: UIView {
func addNavBar() {
let rect = CGRect(x: 10, y: 70, width: 250, height: 100)
let navBarView = UIView(frame: rect)
navBarView.backgroundColor = UIColor.blue
self.addSubview(navBarView)
}
}

Answer 1

self in NavigationBarHelper is not the same object as the view in the view controller. Pass the VC's view as a parameter. There is no need to make NavigationBarHelper a subclass of UIView (in fact it could also be a struct).
class NavigationBarHelper {
func addNavBar(to view: UIView) {
let rect = CGRect(x: 10, y: 70, width: 250, height: 100)
let navBarView = UIView(frame: rect)
navBarView.backgroundColor = UIColor.blue
view.addSubview(navBarView)
}
}
please also stick to naming conventions
class HomeController: UIViewController {
let navBarHelper = NavigationBarHelper()
override func viewDidLoad() {
super.viewDidLoad()
navBarHelper.addNavBar(to: self.view)
}

Answer 2

Instead of creating an object every usage
let NavBar = NavigationBarHelper()
I think it's more robust to make it static like this
class NavigationBarHelper: UIView {
static func addNavBar(view:UIView) {
let rect = CGRect(x: 10, y: 70, width: 250, height: 100)
let navBarView = UIView(frame: rect)
navBarView.backgroundColor = UIColor.blue
view.addSubview(navBarView)
}
}
and call it directly without object creation
NavigationBarHelper.addNavBar(view: self.view)

Answer 3

A Better Alternative for this would be an extension so you don't have to create the special class for this
extension UIView {
func addNavBar() {
let rect = CGRect(x: 10, y: 70, width: 250, height: 100)
let navBarView = UIView(frame: rect)
navBarView.backgroundColor = UIColor.blue
self.addSubview(navBarView)
}
}
And in you UIViewController you can simply write this without creating an object of your helper.
self.view.addNavBar()