通过 TabBarController 呈现模态 ViewController

Question

我有一个主 tabBarController 并且想在点击某个 tabBarItem 时显示一个 viewController modally。

我正在 tabBarController 中加载 viewControllers 作为...

func setupViewControllers() {
    self.tabBar.isHidden = false

    if let firstVC = storyboard?.instantiateViewController(withIdentifier: "first") as? FirstViewController, let secondVC = storyboard?.instantiateViewController(withIdentifier: "second") as? SecondViewController, let thirdVC = storyboard?.instantiateViewController(withIdentifier: "third") as? ThirdViewController, let fourthVC = storyboard?.instantiateViewController(withIdentifier: "fourth") as? FourthViewController, let fifthVC = storyboard?.instantiateViewController(withIdentifier: "fifth") as? FifthViewController {

        let firstNavController = UINavigationController(rootViewController: firstVC)
        let secondNavController = UINavigationController(rootViewController: secondVC)
        let fourthNavController = UINavigationController(rootViewController: fourthVC)
        let fifthNavController = UINavigationController(rootViewController: fifthVC)

        firstNavController.tabBarItem.image = image
        secondNavController.tabBarItem.image = image
        fourthNavController.tabBarItem.image = image
        fifthNavController.tabBarItem.image = image     
        thirdVC.tabBarItem.image = image

        tabBar.tintColor = nil

        //Load tabBar viewControllers
        viewControllers = [homeNavController, postNavController, plusMenuVC, meetupNavController, profileNavController]
    }
}

然后我使 tabBarViewController 符合 UITabBarControllerDelegate 以调用方法...

func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
    if tabBarController.selectedIndex == 2, let thirdVC = viewController as? ThirdViewController {
        thirdVC.modalPresentationStyle = .overFullScreen
        thirdVC.modalTransitionStyle = .crossDissolve
        present(thirdVC, animated: true, completion: nil)
        return false
    } else { return true }
}

然而，以上永远不会被触发。我尝试在 viewDidLoad

中设置

self.delegate = self

我尝试将根导航控制器及其祖先 tabBarController 委托给自己。

似乎没有任何效果，我希望有人能指导我，因为我一直无法调试并找到现有的解决方案...

更新所以我创建了一个 dummyThirdVC 来替换 setupViewControllers() 函数中的 thirdVC 。在 dummyThirdVC 中，我符合 UITabBarControllerDelegate，在 viewDidLoad 中，我设置了 self.tabBarController.delegate = self。然后我把delegate方法输入到这个dummyThirdVC里面，在这个delegate方法里面，我实例化了真正的thirdVC来呈现

delegate 方法终于正确触发，但我现在的问题是，dummyThirdVC 及其视图必须首先加载并出现，然后才能设置和触发 delegate。

我怎么能不显示 dummyThirdVC 而立即显示实例化的真实 thirdVC？我在我的 setupViewControllers 函数中尝试了 dummyThirdVC.viewDidLoad() 但无济于事...

Answer 1

我相信你的支票是错误的。您正在检查 selectedIndex 是否为 2，但是 selectedIndex 的值将始终是实际选项卡栏的选定索引，而不是将要选择的索引，所以您基本上是永远不会达到 selectedIndex 作为 2。

您也不能显示已经激活的视图控制器，并且 thirdVC 在您的 tabBar 中已经激活，因此您会收到错误消息。解决方法是使用 viewController 作为标签栏中图像和标题的占位符，并实例化另一个用于呈现。

func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
    if viewController is ThirdViewController {
        let vcToPresent = storyboard?.instantiateViewController(withIdentifier: "third") as? ThirdViewController
        vcToPresent.modalPresentationStyle = .overFullScreen
        vcToPresent.modalTransitionStyle = .crossDissolve
        present(vcToPresent, animated: true, completion: nil)
        return false
    }
    return true
}

通过 TabBarController 呈现模态 ViewController

Present Modal ViewController via TabBarController

ios

swift

uitabbarcontroller

uitabbar

presentmodalviewcontroller