在两个类之间快速共享信息

Question

我现在正在开发一个选项卡式 View 应用程序，我想知道是否有任何方法可以将我的 FirstViewController.swift 中的信息共享到我的 SecondViewController.swift ？因为我知道 swift 不支持多类继承，所以有没有办法可以在 SecondViewController 中使用 FirstViewController 上的变量和信息？

Answer 1

您需要在 View Controller 上下文之外的模型来存储数据，然后需要一种方法来使用该数据填充这些 View Controller 并提供对模型的引用以从 View Controller 进行更改。您可以通过创建一个符合 UITabBarColtronnerDelegate 的新模型对象来实现此目的，该对象将允许您在选择 View Controller 后访问该 View Controller 。通过将这些关系抽象为协议(protocol)来保持事物的解耦，然后允许您的实现随着应用程序的扩展而独立变化。

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?
    let applicationModel = ApplicationModel()

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        if let tabBarController = window?.rootViewController as? UITabBarController {
            tabBarController.delegate = applicationModel
        }
        return true
    }
}

protocol TabbedViewControllerDelegate {
    var message: String { set get }
}

class ApplicationModel: NSObject, UITabBarControllerDelegate, TabbedViewControllerDelegate {

    var message = "Hello World!"

    func tabBarController(tabBarController: UITabBarController, didSelectViewController viewController: UIViewController) {
        if var tabbedViewController = viewController as? TabbedViewController {
            tabbedViewController.message = message
            tabBarController.delegate = self
        }
    }
}

protocol TabbedViewController {
    var message: String { set get }
    var delegate: TabbedViewControllerDelegate? { get set }
}

class FirstViewController: UIViewController, TabbedViewController {

    var delegate: TabbedViewControllerDelegate?

    var message: String = "" {
        didSet {
            println( "FirstViewController populated with message: \(message)" )
        }
    }

    @IBAction func buttonPressed( sender: AnyObject? ) {
        self.delegate?.message = "Updated message from FirstViewController"
    }
}

class SecondViewController: UIViewController, TabbedViewController {

    var delegate: TabbedViewControllerDelegate?

    var message: String = "" {
        didSet {
            println( "SecondViewController populated with message: \(message)" )
        }
    }

    @IBAction func buttonPressed( sender: AnyObject? ) {
        self.delegate?.message = "Updated message from SecondViewController"
    }
}