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尝试访问TabBar时出现IOS swift致命错误nil异常

nsobject uitabbaritem uitabbar swift4 swift

user1591668 · 技术社区 · 6 年前

   controller.dismiss(animated: false, completion: nil)

但是,正如您从下面的图像中看到的,我的主选项卡栏项没有突出显示,我创建了一个方法,试图突出显示我的主选项卡,但我得到了一个nil异常。首先让我向你展示我的自定义功能所有的标签栏项目点击这里

class HomeProfile: NSObject {
var mycontroller = ControllerEnum()


func TabBarLogic(_ tabBar: UITabBar, didSelect item: UITabBarItem, streamsModel: Int, controller: UIViewController) {

    if tabBar.items?.index(of: item) == 0 {
          tabBar.tintColor = UIColor(hexString: "#004d99")

        if TabBarCounter == 0 {
   // To Refresh 
            let nextViewController = controller.storyboard?.instantiateViewController(withIdentifier: "HomeC") as! HomeC
            controller.present(nextViewController, animated:false, completion: nil)
        } else {
// keeps TableView position but does not highlight Tab           
            controller.dismiss(animated: false, completion: nil)
            let Home = HomeC()
            Home.HighlightTabBar() // Nil exception here
            TabBarCounter = 0
        }

    }
    if tabBar.items?.index(of: item)! == 1 {
        // Search Tab Item
        tabBar.tintColor = UIColor(hexString: "#004d99")
        let nextViewController = controller.storyboard?.instantiateViewController(withIdentifier: "LocalSearchC") as! LocalSearchC
        controller.present(nextViewController, animated:false, completion:nil)
                      TabBarCounter = 1
    }
    if tabBar.items?.index(of: item)! == 2 {
      // Post
    }
    if tabBar.items?.index(of: item)! == 3 {
         // Notification
    }
    if tabBar.items?.index(of: item)! == 4 {
        // Menu
    }

}
  }

此功能与facebook类似,如果您在主页上再次单击“主页”选项卡,则它将刷新“表格”视图;但是,如果您在另一个选项卡上并返回“主页”选项卡,它将保持您的位置;在 标签计数器 检查一下。

class HomeC: UIViewController,UITableViewDataSource,UITableViewDelegate, UITabBarDelegate{

 @IBOutlet weak var TabBar: UITabBar!

 override func viewDidLoad() {
        super.viewDidLoad()
TabBar.delegate = self
      TabBar.selectedItem = TabBar.items![0]
       TabBar.tintColor = UIColor(hexString: "#004d99")
}

  func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
        homeProfile.TabBarLogic(tabBar, didSelect: item, streamsModel: TabCounter,controller: self)

}

func HighlightTabBar() {
    TabBar.delegate = self 
    TabBar.selectedItem = TabBar.items![0] // this fails
    TabBar.tintColor = UIColor(hexString: "#004d99")
}

}

我知道它失败的原因是HighlightTabBar()中的TabBar在调用它时没有对TabBar的引用。我怎样才能使它起作用呢。我一直在看这个 How to programmatically change UITabBar selected index after Dismiss?

1 回复 | 直到 6 年前

Srinivasan_iOS 6 年前

将代码放入应用程序委托或按钮操作中

let appDelegate = UIApplication.shared.delegate as! AppDelegate
let tabBarController = appDelegate.window?.rootViewController as! UITabBarController
tabBarController.selectedIndex = 2