Custom init of UIViewController from storyboard

Question

I tried finding some relevant questions but couldn\'t get anything, hope someone can help.

I set up some UIViewController\'s on a storyboard. I then want to load one

Answer 1

A simplification of my prior answer which is quick and avoids alternative hacky fixes:

Here is a detail view controller you may want to instantiate from storyboard with an objectID set:

import UIKit

class DetailViewController: UIViewController {

    var objectID : Int!

    internal static func instantiate(with objectID: Int) -> DetailViewController {

        let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "DetailViewController") as DetailViewController
        vc.objectID = objectID
        return vc
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        if((objectID) != nil){
            print("Here is my objectID: \(objectID)")
        }
    }
}

Here is how you would use it to push onto a navigation controller with objectID set to 1:

self.navigationController.pushViewController(DetailViewController.instantiate(1), animated: true)

Added a blog post: https://theswiftcook.wordpress.com/2017/02/17/how-to-initialize-a-storyboard-viewcontroller-with-data-without-segues-swift-3-0git/

Link to example on GitHub: https://github.com/hammadzz/Instantiate-ViewController-From-Storyboard-With-Data

Answer 2

Below are two helpers, one is a Storyboard enum, add each and every storyboard in your project as a case under this enum. The name must match the {storyboard_name}.storyboard file. Each view controller in your storyboard should have its storyboard identifier set to the name of the class. This is pretty standard practice.

import UIKit

public enum Storyboard: String {
    case Main
    case AnotherStoryboard
    //case {storyboard_name}

    public func instantiate<VC: UIViewController>(_ viewController: VC.Type) -> VC {
        guard
            let vc = UIStoryboard(name: self.rawValue, bundle: nil)
                .instantiateViewController(withIdentifier: VC.storyboardIdentifier) as? VC
            else { fatalError("Couldn't instantiate \(VC.storyboardIdentifier) from \(self.rawValue)") }

        return vc
    }

    public func instantiateInitialVC() -> UIViewController {

        guard let vc = UIStoryboard(name: self.rawValue, bundle: nil).instantiateInitialViewController() else {
            fatalError("Couldn't instantiate initial viewcontroller from \(self.rawValue)")
        }

        return vc
    }
}

extension UIViewController {
    public static var defaultNib: String {
        return self.description().components(separatedBy: ".").dropFirst().joined(separator: ".")
    }

    public static var storyboardIdentifier: String {
        return self.description().components(separatedBy: ".").dropFirst().joined(separator: ".")
    }
}

Here is how you can instantiate from storyboard with a value set in your view controller. Here is the magic:

import UIKit

class DetailViewController: UIViewController {

    var objectID : Int!
    var objectDetails: ObjectDetails = ObjectDetails()        

    internal static func instantiate(with objectID: Int) -> DetailViewController {

        let vc = Storyboard.Main.instantiate(DetailViewController.self)
        vc.objectID = objectID
        return vc
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        if((objectID) != nil){
            // In this method I use to make a web request to pull details from an API
            loadObjectDetails()
        }
    }
}

(Architecture influenced/copies Kickstarter's open source iOS project)

Answer 3

An (ugly) way to solve this issue:

You can set your let i from an external buffer in your code (AppDelegate variable in this example)

required init?(coder aDecoder: NSCoder) {
    self.i = UIApplication.shared().delegate.bufferForI

    super.init(coder: aDecoder)
}

And when you initiate your UIViewController through Storyboard:

UIApplication.shared().delegate.bufferForI = myIValue
self.navigationController!.pushViewControllerFading(self.storyboard!.instantiateViewController(withIdentifier: "myViewControllerID") as UIViewController)

EDIT: You don't have to pass the value through the AppDelegate. Better answer here.