For my current project we’ve got a design requirement that all screens have a simple “Back” button instead of the default text that iOS provides when pushing a new controller.
I found that Swift’s inheritance model combined with extensions methods make this simple to implement in a re-usable fashion. To start this approach, I implemented a based controller which I called BaseController that manages the title of the backBarButtonItem. This is automatically handled by just inheriting from the BaseController. In the below example we create a new NotificationController using this pattern.
import UIKit
class NotificationController: BaseViewController {
override func viewDidLoad() {
super.viewDidLoad()
}
}
The BaseController only has two lines of code. The first creates a string with the title of the back button. The second calls an extension method that manages the back button title information.
import UIKit
class BaseViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let backTitle = NSLocalizedString("Back", comment: "Back button label")
self.addBackbutton(backTitle)
}
}
The heavy lifting is performed in the UIViewController extension. Using the addBackbutton method to add a new UIBarButtonItem or update the current one’s title. If a new UIBarButtonItem is added the backButtonAction method is added to dismiss the controller on press.
import UIKit
extension UIViewController {
func backButtonAction() {
self.dismissViewControllerAnimated(true, completion: nil)
}
func addBackbutton(title: String) {
if let nav = self.navigationController,
let item = nav.navigationBar.topItem {
item.backBarButtonItem = UIBarButtonItem(title: title, style: UIBarButtonItemStyle.Plain, target: self, action:
#selector(self.backButtonAction))
} else {
if let nav = self.navigationController,
let _ = nav.navigationBar.backItem {
self.navigationController!.navigationBar.backItem!.title = title
}
}
}
}
The full code is available as a gist here.
bencoding 