ios - 使用 UITabBarController 的持久视图

Question

我正在尝试构建一个布局类似于 Apple Music 的应用程序——一个带有持久视图的标签栏导航，可以从应用程序的任何地方访问。视图可以扩展以占据整个屏幕或最小化，静态高度为 80。UI 内置在带有普通UITabBarController. 这是初稿：

这就是我构建它的方式：

class TabbarViewController: UITabBarController {

    override func viewDidLoad() {
        super.viewDidLoad()
        embedLiveFeedbackController()
    }

    private func embedLiveFeedbackController() {
        guard let feedbackController = UIStoryboard(name: "LiveFeedback", bundle: nil).instantiateInitialViewController() as? LiveFeedbackViewController else { return }

        feedbackController.stateDelegate = self
        addChildViewController(feedbackController)
        view.addSubview(feedbackController.view)

        feedbackController.view.translatesAutoresizingMaskIntoConstraints = false
        feedbackController.view.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
        feedbackController.view.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
        feedbackController.view.bottomAnchor.constraint(equalTo: tabBar.topAnchor).isActive = true

        liveFeedbackTopConstraint = feedbackController.view.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor)
        liveFeedbackHeightConstraint = feedbackController.view.heightAnchor.constraint(equalToConstant: Constants.minimizedHeight)

        liveFeedbackHeightConstraint?.isActive = true
        liveFeedbackTopConstraint?.isActive = false

    }
}

我遇到的问题是视图控制器的内容位于持久视图之后并且不完全可见。我尝试过的一件事是将视图控制器限制在持久视图的顶部：

private func constraintViewControllers() {
    guard let vcs = viewControllers else { return }
    guard let topAnchor = liveFeedbackTopAnchor else { return } // a reference to the top anchor of the persistent view

    for viewController in vcs {
        viewController.view.translatesAutoresizingMaskIntoConstraints = false
        viewController.view.bottomAnchor.constraint(equalTo: topAnchor).isActive = true
    }
}

当然，我收到以下错误：

Unable to activate constraint with anchors <NSLayoutYAxisAnchor:0x600000864640 "UILayoutContainerView:0x7fc813f0ea60.bottom"> and <NSLayoutYAxisAnchor:0x60400047b980 "UIView:0x7fc813f08af0.bottom"> because they have no common ancestor.  Does the constraint or its anchors reference items in different view hierarchies?  That's illegal.'

有什么建议如何实施吗？

标签： iosswiftuitabbarcontroller

Answer 1

这是我的建议，我测试了它并且工作正常

创建一个主 viewController 并在其中放置 2 个视图（如图所示）：

-startViewController 
--containerView (your app root viewController/tabBarController goes here)
--persistentView

在启动视图控制器中

class ViewController: UIViewController {

var tabController : TabController!

@IBOutlet weak var containerView: UIView!
@IBOutlet weak var persistentView: UIView!
@IBOutlet weak var persistentBottomConstraint: NSLayoutConstraint!

override func viewDidLoad() {
    super.viewDidLoad()
    
    tabController = TabController.initFromStoryBord()
    
    self.addChild(tabController)
    tabController.view.frame = containerView.bounds
    containerView.addSubview(tabController.view)
    tabController.view.autoresizingMask = [.flexibleHeight, .flexibleWidth]
    
   
    persistantBottomConstraint.constant = tabController.tabBar.frame.height
}
}

然后是 TabBarController 的一个类：

确保为 tabController 设置 Stroyboard ID

class TabController : UITabBarController {
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }

    static func initFromStoryBord() -> TabController {
        let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "TabController") as! TabController
        return vc
    }
}