ios - 在 UITabBarController 中的不同选项卡之间共享公共(public) View

Question

我想创建一个由 UITabBarController 的所有 subview Controller 共享的公共(public) View 。

我试图通过容器 View 来实现这一点，但这为每个 subview Controller 创建了不同的实例。

谢谢!

Answer 1

不幸的是，无法在两个不同的父 View 或两个不同的 View Controller 之间共享 View (每个 View Controller 都有 Root View )。

https://developer.apple.com/documentation/uikit/uiview/1622616-addsubview

Views can have only one superview. If view already has a superview and that view is not the receiver, this method removes the previous superview before making the receiver its new superview.

但是您可以通过创建包含适当属性的共享数据模型来模拟相同的行为，以在不同的 View Controller 上显示相同的 View 。

struct ViewModel {
    let frame: CGRect
    let backgroundColor: UIColor
    // other properties that identify view state 
}

class FirstViewController: UIViewController {
    var model: ViewModel?

    @IBOutlet weak var customView: UIView! // view that you want to customize from ViewModel. You can create it programmatically.

    override func viewDidLoad() {
        super.viewDidLoad()

        guard let viewModel = model else { return }

        customView.frame = viewModel.frame
        customView.backgroundColor = viewModel.backgroundColor
    }
}

class SecondViewController: UIViewController {
    var model: ViewModel?

    @IBOutlet weak var customView: UIView! // view that you want to customize from ViewModel. You can create it programmatically.

    override func viewDidLoad() {
        super.viewDidLoad()

        guard let viewModel = model else { return }

        customView.frame = viewModel.frame
        customView.backgroundColor = viewModel.backgroundColor
    }
}

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool {
        // Hierarchy of view controllers is created by storyboard (UITabBarController contains FirstViewController & SecondViewController)
        let mainStoryboard = UIStoryboard(name: "Main", bundle: nil)

        let tabBarController = mainStoryboard.instantiateInitialViewController() as! UITabBarController

        let viewModel = ViewModel(frame: CGRect(x: 10, y: 10, width: 20, height: 20), backgroundColor: UIColor.cyan)
        (tabBarController.viewControllers[0] as! FirstViewController).model = viewModel
        (tabBarController.viewControllers[1] as! SecondViewController).model = viewModel

        window = UIWindow(frame: UIScreen.main.bounds)
        window.rootViewController = tabBarController 

        return true
    }
}