.NET MAUI（.NET 7.0）macOS平台如何修改标题栏颜色？

• 直接修改macOS原生层样式
  对于.NET MAUI的macOS应用，部分Shell控件的样式由原生NSView控制，单纯XAML层级修改可能无法覆盖。可在Platforms/MacCatalyst/AppDelegate.cs中添加原生代码调整：

  public override bool FinishedLaunching(UIApplication application, NSDictionary launchOptions)
  {
      // 调整Shell导航栏背景色与按钮颜色
      UINavigationBar.Appearance.BackgroundColor = UIColor.FromRGB(30, 30, 30);
      UINavigationBar.Appearance.TintColor = UIColor.White;
      
      // 调整TabBar样式（若使用TabBar）
      UITabBar.Appearance.BackgroundColor = UIColor.FromRGB(30, 30, 30);
      UITabBar.Appearance.TintColor = UIColor.White;
      
      return base.FinishedLaunching(application, launchOptions);
  }
  

• 使用自定义Renderer（MacCatalyst）
  若需更精细的控件样式定制，创建Shell的自定义Renderer：

  [assembly: ExportRenderer(typeof(AppShell), typeof(CustomShellRenderer))]
  namespace YourAppName.Platforms.MacCatalyst
  {
      public class CustomShellRenderer : ShellRenderer
      {
          protected override IShellTabBarAppearanceTracker CreateTabBarAppearanceTracker()
          {
              return new CustomTabBarAppearanceTracker();
          }
          
          protected override IShellNavigationBarAppearanceTracker CreateNavigationBarAppearanceTracker()
          {
              return new CustomNavigationBarAppearanceTracker();
          }
      }
      
      public class CustomTabBarAppearanceTracker : IShellTabBarAppearanceTracker
      {
          public void Dispose() { }
          public void ResetAppearance(UITabBarController controller) { }
          
          public void SetAppearance(UITabBarController controller, ShellAppearance appearance)
          {
              controller.TabBar.BackgroundColor = UIColor.FromRGB(20, 20, 20);
              controller.TabBar.UnselectedItemTintColor = UIColor.Gray;
          }
          
          public void UpdateLayout(UITabBarController controller) { }
      }
      
      public class CustomNavigationBarAppearanceTracker : IShellNavigationBarAppearanceTracker
      {
          public void Dispose() { }
          public void ResetAppearance(UINavigationController controller) { }
          
          public void SetAppearance(UINavigationController controller, ShellAppearance appearance)
          {
              controller.NavigationBar.BackgroundColor = UIColor.FromRGB(20, 20, 20);
              controller.NavigationBar.TitleTextAttributes = new UIStringAttributes
              {
                  ForegroundColor = UIColor.White
              };
          }
          
          public void UpdateLayout(UINavigationController controller) { }
      }
  }
  

• 检查XAML样式优先级
  确保XAML样式未被更高优先级设置覆盖：

  • 避免在控件本地直接设置BackgroundColor等属性，优先使用全局样式
  • 在App.xaml中确认样式资源的引用顺序，后定义的样式会覆盖前序样式

内容的提问来源于stack exchange，提问作者Arthur Andrade