Swift 4 Split View Controller 详细信息替换 Master

Question

我刚刚开始构建一个应用程序，现在我正在添加 2 个拆分视图控制器，在我的 Main.storyboard 中它看起来像这张图片

我将以下代码添加到我的 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.
        }
    }


}

这是我的详细信息：

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()
        }
    }


}

我的问题是当我运行我的应用程序并转到拆分视图控制器并在主视图中选择一个项目时，它没有转到详细信息，而是替换了主视图。

我有一个示例应用程序，它只是拆分视图控制器，我在示例应用程序的 App Delegate 文件中注意到应用程序中有此代码（_ 应用程序：UIApplication，didFinishLaunchingWithOptions launchOptions：[UIApplicationLaunchOptionsKey：Any]？） -> 布尔方法：

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 

还有这个方法：

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
    }

我对这段代码的问题是我的拆分视图控制器不是初始控制器，而我的 splitViewController 方法存在问题，我有 2 个拆分视图控制器，我只能指定其中的 1 个。如何在不使其成为初始控制器的情况下获得此拆分视图控制器？

Answer 1

您的大师班必须实现 UISplitViewControllerDelegate。 所以你需要做的第一件事：

class ContactsMaster: UITableViewController,UISplitViewControllerDelegate {

并在你的 master 中覆盖这个函数：

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

然后在 viewDidLoad(master class) 中添加以下代码：

self.splitViewController!.delegate = self;

self.splitViewController!.preferredDisplayMode = UISplitViewControllerDisplayMode.AllVisible

self.extendedLayoutIncludesOpaqueBars = true  

我认为你跳过了配置 splitviewcontroller 的许多步骤，如果你想完全理解，你可以阅读为它编写的许多教程之一，例如：

http://nshipster.com/uisplitviewcontroller/

Answer 2

您是否偶然忘记在 Storyboard 中为您的 Detail VC 设置 ContactsDetail 类？