Thread 1 fatal error init coder has not been implemented

] (f7e1c44709ce595200c0c20a804217d5.jp/p>

Now I’m making my first app, and I’m displaying a list of articles like the picture above. Tap an article to see the details of the article. When you click the favorite button, the button color changes. I am trying to make an application that can switch between the article list and the favorite article list with the toolbar below.
When the favorite button is clicked, the reaml database is checked. If the id of the article is included, «remove» is not included. In addition, I am trying to write a code considering the design pattern with MVP for studying.

class ArticleTableViewController: UITableViewController {
 var articles: [Article] = [] // array containing articles
...
override func tableView (_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        let article = articles [indexPath.row]
        let vc = UIStoryboard (name: "ArticleContent", bundle: nil) .instantiateInitialViewController ()! as! ArticleContentViewController
        vc.article.id = article.id
        vc.article.content = article.content
        self.navigationController? .pushViewController (vc, animated: true)
        // pass id and article content to ArticleCOntentViewController
    }
}

import RealmSwift
class RMArticle: Object {
    @objc dynamic var id: Int = 0
    @objc dynamic var content: String = ""
}

protocol ArticleView: class {
    func updateFavoriteButtonTitle (_ title: String)
}
class ArticleContentViewController: UIViewController, ArticleView {
    let article = RMArticle ()
    private let presenter: ArticlePresenter
    @IBOutlet weak var favorite: UIButton!
    init (article: RMArticle, favoritePresenter: FavoritePresenter) {
        self.presenter = ArticleViewPresenter (article: article, favoritePresenter: favoritePresenter)
        super.init (nibName: nil, bundle: nil)
        self.presenter.view = self
    }
    required init? (coder aDecoder: NSCoder) {
        fatalError ("init (coder :) has not been implemented")
    }
    override func viewDidLoad () {
        super.viewDidLoad ()
        print (article.id)
        print (article.content)
        // Do any additional setup after loading the view.
    }

As mentioned above, RMArticle instance has member variables id and content, receives the value in that instance, and later saves this instance in realm when saving. (When you actually display an article, specify the id and hit the API, so you don’t need to save the content, but you don’t know where to define the content …)

When I tap the article with this code,Thread 1: Fatal error: init (coder :) has not been implementedis displayed.

required init? (coder aDecoder: NSCoder) {
Super.init (coder: aDecoder)
        fatalError ("init (coder :) has not been implemented")
    }

If i do the above, you will be toldProperty'self.presenter'not initialized at super.init call. I think it has been initialized …

I didn’t understand the cause well, so I asked a question. Thank you.

Swift’s strict initialization rules are great. They help prevent an entire category of bugs that were especially common in Objective-C. However, when working with Objective-C frameworks, particularly UIKit, these rules can be frustrating.

When you subclass UIViewController and UIView and provide your own initializer, the compiler will prompt you to add the following required initializer:

required init?(coder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

For view controllers, init(nibName:bundle:) is the designated initializer, but init(coder:) is required by the NSCoding protocol. It must be implemented not only because of the protocol, but because this is the initializer that Interface Builder calls when automatically instantiating UIViewController subclasses from storyboards or xibs. The same applies to UIView subclasses.

However, if you do not use Interface Builder, then init(coder:) is irrelevant and will never be called. It is annoying boilerplate. But the real problem is that Xcode (and presumably other editors) will offer init(coder:) as an auto-complete option when initializing your view or view controller. That is not ideal, because it is not a valid way to initialize your custom view or view controller. Luckily, you can use Swift’s @available attribute to prevent this, which also has the benefit of more clearly communicating that you should not use this initializer.

@available(*, unavailable)
required init?(coder: NSCoder) {
    fatalError("(#function) has not been implemented")
}

Now, at compile-time, this initializer is inaccessible. Or technically, at “auto-complete while you type time”.

You might have the idea of putting this in an extension or a protocol, so that you can avoid typing the boilerplate for every UIView and UIViewController subclass. Unfortunately, that is not possible because required initializers must be provided in subclass declarations. So, using @available is the best we can do.

UPDATE: Thanks to JP for pointing out that there’s a SwiftLint rule for exactly this. Unfortunately, it does not currently support autocorrect.