iPad端UITabBarItem标题文本截断（iPhone端显示正常）

问题原因 #

iPad的UITabBar默认采用inline布局（图标与文字横向并排展示），而iPhone默认是stacked布局（图标在上、文字在下）。你当前为所有布局统一设置了18号粗体字体，inline布局下每个TabBarItem的可用宽度不足以容纳大字体的完整标题，导致文本被截断。

解决方案 #

方案1：为iPad的inline布局单独设置更小字体 #

针对不同布局类型配置差异化字体，保证inline布局下标题能完整显示：

class HomeTabBarController: UITabBarController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let tabBarAppearance = UITabBarAppearance()
        // iPhone stacked布局使用18号粗体
        let stackedFont = UIFont.boldSystemFont(ofSize: 18)
        // iPad inline布局使用更小的字体（比如14号粗体）
        let inlineFont = UIFont.boldSystemFont(ofSize: 14)
        
        // Stacked布局属性
        let stackedSelectedAttrs: [NSAttributedString.Key: Any] = [
            .font: stackedFont,
            .foregroundColor: UIColor.orange
        ]
        let stackedNormalAttrs: [NSAttributedString.Key: Any] = [
            .font: stackedFont,
            .foregroundColor: UIColor.black
        ]
        
        // Inline布局属性
        let inlineSelectedAttrs: [NSAttributedString.Key: Any] = [
            .font: inlineFont,
            .foregroundColor: UIColor.orange
        ]
        let inlineNormalAttrs: [NSAttributedString.Key: Any] = [
            .font: inlineFont,
            .foregroundColor: UIColor.black
        ]
        
        // 配置Stacked布局样式
        tabBarAppearance.stackedLayoutAppearance.normal.titleTextAttributes = stackedNormalAttrs
        tabBarAppearance.stackedLayoutAppearance.selected.titleTextAttributes = stackedSelectedAttrs
        
        // 配置Inline布局样式
        tabBarAppearance.inlineLayoutAppearance.normal.titleTextAttributes = inlineNormalAttrs
        tabBarAppearance.inlineLayoutAppearance.selected.titleTextAttributes = inlineSelectedAttrs
        
        // 配置紧凑型Inline布局样式
        tabBarAppearance.compactInlineLayoutAppearance.normal.titleTextAttributes = inlineNormalAttrs
        tabBarAppearance.compactInlineLayoutAppearance.selected.titleTextAttributes = inlineSelectedAttrs

        tabBar.standardAppearance = tabBarAppearance
        // iOS 15+需要同步设置scrollEdgeAppearance
        if #available(iOS 15.0, *) {
            tabBar.scrollEdgeAppearance = tabBarAppearance
        }
    }
}

方案2：强制iPad使用stacked布局 #

如果产品允许iPad端采用和iPhone一致的堆叠布局，可通过修改TabBar的itemPositioning实现：

class HomeTabBarController: UITabBarController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // 原有的Appearance配置代码保持不变
        let tabBarAppearance = UITabBarAppearance()
        let tabFont = UIFont.boldSystemFont(ofSize: 18)
        
        let selectedAttributes: [NSAttributedString.Key: Any] = [
            .font: tabFont,
            .foregroundColor: UIColor.orange
        ]
        let normalAttributes: [NSAttributedString.Key: Any] = [
            .font: tabFont,
            .foregroundColor: UIColor.black
        ]
        
        tabBarAppearance.stackedLayoutAppearance.normal.titleTextAttributes = normalAttributes
        tabBarAppearance.stackedLayoutAppearance.selected.titleTextAttributes = selectedAttributes
        
        tabBarAppearance.inlineLayoutAppearance.normal.titleTextAttributes = normalAttributes
        tabBarAppearance.inlineLayoutAppearance.selected.titleTextAttributes = selectedAttributes

        tabBarAppearance.compactInlineLayoutAppearance.normal.titleTextAttributes = normalAttributes
        tabBarAppearance.compactInlineLayoutAppearance.selected.titleTextAttributes = selectedAttributes

        tabBar.standardAppearance = tabBarAppearance
        if #available(iOS 15.0, *) {
            tabBar.scrollEdgeAppearance = tabBarAppearance
        }
    }

    override func viewWillLayoutSubviews() {
        super.viewWillLayoutSubviews()
        // 检测设备类型，强制iPad使用stacked布局
        if UIDevice.current.userInterfaceIdiom == .pad {
            tabBar.itemPositioning = .stacked
            // 可选：调整item间距，优化显示效果
            tabBar.itemSpacing = 8
        }
    }
}

方案3：调整标题换行模式（备选） #

通过设置标题的换行模式，让文本自动换行或缩小适配，但这种方法可能导致文字过小影响可读性，仅作为备选：

在属性字典中添加NSAttributedString.Key.lineBreakMode：

let normalAttributes: [NSAttributedString.Key: Any] = [
    .font: tabFont,
    .foregroundColor: UIColor.black,
    .lineBreakMode: NSLineBreakMode.byWordWrapping
]

内容的提问来源于stack exchange，提问作者Avinash Kumar