ios - 如何在模态 Viewcontroller 被解散后更新父 Viewcontroller 的 View

Question

我有一个 UIBarButtonItem ，当它被关闭时，我想从模式 viewController 的值更新它。目前我只能通过获取当前可见的 viewController 来做到这一点，这是我不知道的'想要。有没有一种方法可以在关闭模态视图 Controller 后更新父 View Controller 。

class HomeViewController: UIViewController {

    @IBOutlet weak var accountButton: UIBarButtonItem!

    override func viewWillAppear(_ pAnimated: Bool) {
        super.viewWillAppear(pAnimated)
        self.accountButton.title = User.current!.firstName
   }

@IBAction func accountButton(_ pSender: UIBarButtonItem) {
        let editUserAccountVC = UIStoryboard.fs_instantiateFromStoryboard("Main", identifier: "EditUserAccountViewController") as! EditUserAccountViewController
        let navVC = UINavigationController(rootViewController: editUserAccountVC)
        navVC.view.tintColor = self.view.tintColor
        self.present(navVC, animated: true)
       }
   }
}

这是编辑后关闭的模态

class EditUserAccountViewController: UIViewController {

    var firstName: String?

    @IBAction func saveButton(_ sender: Any) {
        self.dismiss(animated: true) {
            if let thePresentedViewController = self.presentingViewController as? HomeViewController {
                thePresentedViewController.accountButton.title = self.firstName
            }
        }    
    }
}

Answer 1

我认为您应该在模态 Controller 实例中存储对父 Controller 的引用。您可以使用协议(protocol)使其更通用。声明以下协议(protocol):

protocol AccountButtonProvider: AnyObject {
    var accountButtonTitle: String? { set get }
}

AnyObject 需要将对 AccountButtonProvider 的引用声明为 weak。我想您将需要它来避免内存泄漏。

使 HomeViewController 符合 AccountButtonProvider:

extension HomeViewController: AccountButtonProvider {
    var accountButtonTitle: String? {
        set {
            accountButton.title = newValue
        }
        get {
            return accountButton.title
        }
    }
}

然后将以下属性添加到 EditUserAccountViewController:

weak var accountButtonProvider: AccountButtonProvider?

在呈现 EditUserAccountViewController 之前初始化此属性。为此，将 editUserAccountVC.accountButtonProvider = self 添加到 accountButton(_:):

@IBAction func accountButton(_ pSender: UIBarButtonItem) {
    let editUserAccountVC = UIStoryboard.fs_instantiateFromStoryboard("Main", identifier: "EditUserAccountViewController") as! EditUserAccountViewController
    editUserAccountVC.accountButtonProvider = self
}

你还应该修改saveButton(_:):

@IBAction func saveButton(_ sender: Any) {
    self.dismiss(animated: true) {
        self.accountButtonProvider?.actionButtonTitle = self.firstName
    }
}

本文中的所有代码都在 Xcode 10.2.1 中进行了测试。我使用的是 Swift 5。