Swift 4 Split View Controller Detail Replaces Master

Question

I just started building an app and right now I am adding 2 Split View Controllers, in my Main.storyboard it looks like this image

I added the following code to my Master:

import UIKit

class ContactsMaster: UITableViewController {

    var ContactsDetailController: ContactsDetail? = nil
    var objects = [Any]()


    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        navigationItem.leftBarButtonItem = editButtonItem

        let addButton = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(insertNewObject(_:)))
        navigationItem.rightBarButtonItem = addButton
        if let split = splitViewController {
            let controllers = split.viewControllers
            ContactsDetailController = (controllers[controllers.count-1] as! UINavigationController).topViewController as? ContactsDetail
        }
    }

    override func viewWillAppear(_ animated: Bool) {
        clearsSelectionOnViewWillAppear = splitViewController!.isCollapsed
        super.viewWillAppear(animated)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @objc
    func insertNewObject(_ sender: Any) {
        objects.insert(NSDate(), at: 0)
        let indexPath = IndexPath(row: 0, section: 0)
        tableView.insertRows(at: [indexPath], with: .automatic)
    }

    // MARK: - Segues

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "showContactDetail" {
            if let indexPath = tableView.indexPathForSelectedRow {
                let object = objects[indexPath.row] as! NSDate
                let controller = (segue.destination as! UINavigationController).topViewController as! ContactsDetail
                controller.detailItem = object
                controller.navigationItem.leftBarButtonItem = splitViewController?.displayModeButtonItem
                controller.navigationItem.leftItemsSupplementBackButton = true
            }
        }
    }

    // MARK: - Table View

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return objects.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)

        let object = objects[indexPath.row] as! NSDate
        cell.textLabel!.text = object.description
        return cell
    }

    override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
        // Return false if you do not want the specified item to be editable.
        return true
    }

    override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
        if editingStyle == .delete {
            objects.remove(at: indexPath.row)
            tableView.deleteRows(at: [indexPath], with: .fade)
        } else if editingStyle == .insert {
            // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view.
        }
    }


}

And here is my Detail:

import UIKit

class ContactsDetail: UIViewController {

    @IBOutlet weak var detailDescriptionLabel: UILabel!


    func configureView() {
        // Update the user interface for the detail item.
        if let detail = detailItem {
            if let label = detailDescriptionLabel {
                label.text = detail.description
            }
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        configureView()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    var detailItem: NSDate? {
        didSet {
            // Update the view.
            configureView()
        }
    }


}

My problem is when I run my app and goto the Split View Controller and select an item in the Master, it does not goto the Detail, but instead replaces the master.

I have a sample app that is just the Split View Controller and I noticed in the App Delegate file of the sample app there is this code in the application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool method:

let splitViewController = window!.rootViewController as! UISplitViewController
        let navigationController = splitViewController.viewControllers[splitViewController.viewControllers.count-1] as! UINavigationController
        navigationController.topViewController!.navigationItem.leftBarButtonItem = splitViewController.displayModeButtonItem
        splitViewController.delegate = self 

And there is also this method:

func splitViewController(_ splitViewController: UISplitViewController, collapseSecondary secondaryViewController:UIViewController, onto primaryViewController:UIViewController) -> Bool {
        guard let secondaryAsNavController = secondaryViewController as? UINavigationController else { return false }
        guard let topAsDetailController = secondaryAsNavController.topViewController as? DetailViewController else { return false }
        if topAsDetailController.detailItem == nil {
            // Return true to indicate that we have handled the collapse by doing nothing; the secondary controller will be discarded.
            return true
        }
        return false
    }

My problem with this code is that my Split View Controller is not the inital controller and my problem with the splitViewController method, I have 2 split view controllers, I can only specificity 1 of them. How do I get this split view controller without making it the inital controller?

Answer 1

your master class must implement UISplitViewControllerDelegate. so first thing you need to do :

class ContactsMaster: UITableViewController,UISplitViewControllerDelegate {

and override this function in your master:

func splitViewController(splitViewController: UISplitViewController, collapseSecondaryViewController secondaryViewController: UIViewController, ontoPrimaryViewController primaryViewController: UIViewController) -> Bool {
return true    
}

then in viewDidLoad(master class) add following cods:

self.splitViewController!.delegate = self;

self.splitViewController!.preferredDisplayMode = UISplitViewControllerDisplayMode.AllVisible

self.extendedLayoutIncludesOpaqueBars = true  

I think you skip many steps for configuring splitviewcontroller, if you want to understand all the way you can read one of many tutorials written for it, like:

http://nshipster.com/uisplitviewcontroller/