如何在不启用兼容标志的情况下修改iOS 26中UINavigationBar按钮样式？

问题说明 #

更新Xcode并针对iOS 26构建应用后，UINavigationBar上的按钮默认变为大圆角矩形外观，需在不启用UIDesignRequiresCompatibility兼容标志的前提下，恢复旧版按钮样式，同时保留iOS 26的导航栏透明效果。

样式对比 #

• 旧版外观（兼容标志开启）：
  
• iOS 26新版外观（兼容标志关闭）：
  

解决方案 #

1. 全局统一配置（推荐） #

在App启动阶段（如AppDelegate的didFinishLaunchingWithOptions或SceneDelegate的scene(_:willConnectTo:options:)）添加代码，通过UIAppearance统一设置所有导航栏按钮的旧版样式：

// 配置按钮文字属性，匹配旧版字体
UIBarButtonItem.appearance().setTitleTextAttributes([
    .font: UIFont.systemFont(ofSize: 17)
], for: .normal)

// 自定义按钮背景样式
let barButtonAppearance = UIBarButtonAppearance()
barButtonAppearance.configureWithDefaultBackground()
barButtonAppearance.background.cornerRadius = 4 // 旧版按钮圆角一般为4-6，可按需微调
barButtonAppearance.backgroundColor = .clear // 保留透明效果
barButtonAppearance.normal.titleTextAttributes = [
    .foregroundColor: UIColor.systemBlue
]

// 将样式应用到导航栏
UINavigationBar.appearance().standardAppearance.buttonAppearance = barButtonAppearance
UINavigationBar.appearance().scrollEdgeAppearance = barButtonAppearance

2. 单个按钮自定义配置 #

若仅需修改特定页面的导航栏按钮，直接为目标UIBarButtonItem设置自定义外观：

let customAppearance = UIBarButtonAppearance()
customAppearance.configureWithDefaultBackground()
customAppearance.background.cornerRadius = 4
customAppearance.backgroundColor = .clear

let customButton = UIBarButtonItem(title: "返回", style: .plain, target: self, action: #selector(backAction))
customButton.standardAppearance = customAppearance
navigationItem.leftBarButtonItem = customButton

补充：系统返回按钮适配 #

若需修改系统自带的返回按钮样式，需额外配置：

let backButtonAppearance = UIBarButtonAppearance()
backButtonAppearance.configureWithDefaultBackground()
backButtonAppearance.background.cornerRadius = 4
UINavigationBar.appearance().standardAppearance.backButtonAppearance = backButtonAppearance

内容的提问来源于stack exchange，提问作者Ant