如果您获得了tabBarController的引用（例如从UIViewController），您可以执行以下操作：

if let tabItems = tabBarController?.tabBar.items {
    // In this case we want to modify the badge number of the third tab:
    let tabItem = tabItems[2]
    tabItem.badgeValue = "1"
}

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在UITabBarController中，它将是tabBar.items，而不是tabBarController?.tabBar.items
删除徽章：

tabItem.badgeValue = nil

型

下面的行可以帮助您在UITabBerItem中显示徽章

tabBarController?.tabBar.items?[your_desired_tabBer_item_number].badgeValue = value

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如果需要，也可以为标记值设置一个空字符串，以获得一个红色圆圈：

tabBarController?.tabBar.items?.last?.badgeValue = ""

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的数据

在ViewDidAppear中设置badgeValue。否则，它可能不会从应用程序加载中出现。

import UIKit
class TabBarController: UITabBarController {
override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    self.tabBar.items![2].badgeValue = "7"
}
}

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没有安全检查，因为您通常可以确保TabBar具有n个选项卡。

我将@维克托代码放在扩展中，以使代码在视图中更小。

import UIKit
extension UITabBar {
    func addBadge(index:Int) {
        if let tabItems = self.items {
            let tabItem = tabItems[index]
            tabItem.badgeValue = "●"
            tabItem.badgeColor = .clear
            tabItem.setBadgeTextAttributes([NSAttributedString.Key.foregroundColor: UIColor.red], for: .normal)
        }
    }
    func removeBadge(index:Int) {
        if let tabItems = self.items {
            let tabItem = tabItems[index]
            tabItem.badgeValue = nil
        }
    }
    
 }
Application: 
 tabBarController?.tabBar.addBadge(index: 1)
 tabBarController?.tabBar.removeBadge(index: 1)

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感谢@Lepidopteron，即时解决我.此外，您可以使用所选标签索引的索引来执行：

let tabItems = self.tabBarController?.tabBar.items as NSArray!
    var selectedIndex = tabBarController!.selectedIndex //here 
    let tabItem = tabItems![selectedIndex] as! UITabBarItem
    tabItem.badgeValue = "2"

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从this帖子获得参考

func showHideInnerBagde(value:String,indexValue:Int) {
        if let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
           let sceneDelegate = windowScene.delegate as? SceneDelegate,
           let navController = sceneDelegate.window?.rootViewController as? UINavigationController,
           let visibleController = navController.visibleViewController,
           let tabbarController = visibleController as? UITabBarController,
           tabbarController.tabBar.items?.indices.contains(2) ?? false {
            
            let tabIndex = indexValue
            tabbarController.tabBar.items?[tabIndex].badgeValue = value
            tabbarController.tabBar.items?[tabIndex].badgeColor = UIColor.clear
            
            let attributes: [NSAttributedString.Key: Any] = [
                NSAttributedString.Key.foregroundColor: UIColor.red,
                NSAttributedString.Key.font: UIFont.systemFont(ofSize: 12) // Set your desired font
            ]
            tabbarController.tabBar.items?[tabIndex].setBadgeTextAttributes(attributes, for: .normal)
        } else {
            // Handle the case when the conditions are not met or the tab at index 2 does not exist.
            print("Unable to set badge value and text attributes.")
        }
    }

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