Some seemingly useless cruft when deriving from UINavigationController in swift

Question

Why do I need so much (seemingly useless) pass through code that objc did not require in a similar derivation:

class myNavigationController: UINavigationController {

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

override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) {
    super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)
}
...

repeat ad nauseam for every single view controller of mine loaded from xib.

In the case above, is it necessary to override the init function if the only thing you do in your init is to call the super? — dfrib, Dec 16 '15 at 11:57
Right. That's exactly what I'm asking: why I'm required to write an essentially a noop. To avoid some hack/kludge in swift frontend maybe? I'd rather not have to guess — Anton Tropashko, Dec 16 '15 at 12:21
My question was if you cant just remove your override if you know that it will only contain the super.init? (And it's really a question, haven't tried it myself for this example :) ) — dfrib, Dec 16 '15 at 12:22
(if you remove your override init(...) and just use your super's view by default, you can also remove the required init?(:NSCoder) ) — dfrib, Dec 16 '15 at 12:29
No. You can't remove both of them. If you do that you will get something like .../myExtendedSessionNavigationController.swift:19:1: 'required' initializer 'init(coder:)' must be provided by subclass of 'UINavigationController' — Anton Tropashko, Dec 16 '15 at 12:46
removing init(let rootViewController: UIViewController) { super.init(rootViewController:root) } along with the other two take care of this. Thank you. — Anton Tropashko, Dec 16 '15 at 13:13

score 2 · Accepted Answer · edited May 23 '17 at 12:22

This should not be an issue if your don't want to overload the designated initializer init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: NSBundle?) your UINavigationController subclass. If you just want to make use of the default (super) initializer, you can remove both those methods from your class.

I.e., the following class

// MyNavigationController.swift
import UIKit

class MyNavigationController: UINavigationController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // I don't want to make use of this ...
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // ... nor this
    }

    // Things I do want to do with my nav. controller
}

can be reduced to

// MyNavigationController.swift
import UIKit

class MyNavigationController: UINavigationController {

    // Things I do want to do with my nav. controller
}

Without any errors. (Verified in Swift 2.0, Xcode 7.2, simulator: iOS 9.2). This is expected behavior, see e.g. the accepted answer in thread 'required' initializer 'init(coder:)' must be provided by subclass of 'UITableViewCell'`.

If you still get an error when removing these for this subclass type, please give some details regarding your use of the class / Xcode version etc.

Some seemingly useless cruft when deriving from UINavigationController in swift

1 Answers1