iOS Swift中如何让UITabBarController默认取消所有标签选中状态？

当然可以实现，核心思路是让UITabBarController默认加载指定页面，但通过自定义TabBar的外观，让所有标签项视觉上处于未选中状态，用户点击后再恢复正常的选中样式。以下是两种可靠的实现方式：

方法1：通过修改TabBarItem的选中样式实现 #

这种方式直接操作TabBarItem的图片和颜色属性，兼容性覆盖iOS 10+：

class CustomTabBarController: UITabBarController, UITabBarControllerDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        delegate = self
        
        // 默认展示第一个页面（按需修改索引）
        selectedIndex = 0
        
        // 初始状态：让所有标签看起来未选中
        resetTabBarToUnselectedState()
    }
    
    private func resetTabBarToUnselectedState() {
        guard let items = tabBar.items else { return }
        let unselectedColor = tabBar.unselectedItemTintColor ?? .systemGray
        
        // 临时把选中颜色改成未选中颜色
        tabBar.tintColor = unselectedColor
        
        // 让所有TabBarItem的选中图片和默认图片一致
        for item in items {
            if let normalImage = item.image {
                item.selectedImage = normalImage.withRenderingMode(.alwaysOriginal)
            }
        }
    }
    
    // 用户点击标签时，恢复正常选中样式
    func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
        guard let selectedItem = tabBar.selectedItem else { return }
        let selectedColor = UIColor.systemBlue // 自定义你的选中颜色
        
        // 先重置所有标签为未选中状态
        resetTabBarToUnselectedState()
        
        // 设置当前选中标签的样式
        tabBar.tintColor = selectedColor
        if let normalImage = selectedItem.image {
            selectedItem.selectedImage = normalImage.withTintColor(selectedColor, renderingMode: .alwaysOriginal)
        }
    }
}

方法2：使用UITabBarAppearance（iOS 13+） #

iOS 13及以上推荐使用UITabBarAppearance来统一管理TabBar的外观，代码更简洁：

class CustomTabBarController: UITabBarController, UITabBarControllerDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        delegate = self
        
        selectedIndex = 0
        setupInitialTabBarAppearance()
    }
    
    private func setupInitialTabBarAppearance() {
        let unselectedColor = tabBar.unselectedItemTintColor ?? .systemGray
        let appearance = UITabBarAppearance()
        
        // 让选中状态的样式和未选中一致
        appearance.stackedLayoutAppearance.selected.iconColor = unselectedColor
        appearance.stackedLayoutAppearance.selected.titleTextAttributes = [
            NSAttributedString.Key.foregroundColor: unselectedColor
        ]
        
        tabBar.standardAppearance = appearance
        if #available(iOS 15.0, *) {
            tabBar.scrollEdgeAppearance = appearance
        }
    }
    
    func tabBarController(_ tabBarController: UITabBarController, didSelect viewController: UIViewController) {
        let selectedColor = UIColor.systemBlue
        let unselectedColor = tabBar.unselectedItemTintColor ?? .systemGray
        let appearance = UITabBarAppearance()
        
        // 设置选中状态样式
        appearance.stackedLayoutAppearance.selected.iconColor = selectedColor
        appearance.stackedLayoutAppearance.selected.titleTextAttributes = [
            NSAttributedString.Key.foregroundColor: selectedColor
        ]
        
        // 保持未选中状态样式不变
        appearance.stackedLayoutAppearance.normal.iconColor = unselectedColor
        appearance.stackedLayoutAppearance.normal.titleTextAttributes = [
            NSAttributedString.Key.foregroundColor: unselectedColor
        ]
        
        tabBar.standardAppearance = appearance
        if #available(iOS 15.0, *) {
            tabBar.scrollEdgeAppearance = appearance
        }
    }
}

关键注意事项 #

1. 我们并没有修改UITabBarController的selectedIndex核心逻辑，只是改变了视觉表现，这样系统的页面切换逻辑依然正常工作。
2. 必须设置UITabBarControllerDelegate，否则无法在用户点击时恢复选中样式。
3. 如果使用自定义图片，要确保图片的renderingMode设置正确（比如.alwaysOriginal），避免颜色被系统默认 tint 覆盖。

内容的提问来源于stack exchange，提问作者Sachu_