Flutter iOS应用通过Mac Designed for iPad运行时，如何实现鼠标光标切换？

问题场景 #

现有一款iOS Flutter应用，通过Xcode的Mac Designed for iPad目标在macOS运行时，按钮或MouseRegion组件无法切换鼠标光标；但直接以macOS为目标运行测试应用时光标切换正常。主应用因结构复杂、依赖大量不兼容macOS的插件，只能采用Mac Designed for iPad方式运行。

原因分析 #

Mac Designed for iPad本质是iOS应用的macOS兼容运行层，原生iOS系统无鼠标交互逻辑，Flutter默认的光标切换逻辑（依赖macOS原生的鼠标事件处理）在该兼容层中未被正确触发。

解决方案 #

方案1：手动监听PointerHoverEvent切换光标 #

通过Listener组件监听鼠标悬停/离开事件，手动调用SystemMouseCursor切换光标：

Listener(
  onPointerHover: (PointerHoverEvent event) {
    SystemMouseCursor.click.applyOverlay();
  },
  onPointerExit: (PointerExitEvent event) {
    SystemMouseCursor.basic.applyOverlay();
  },
  child: ElevatedButton(
    onPressed: () {},
    child: const Text("测试按钮"),
  ),
)

可以将这段逻辑封装成通用组件，避免重复编写代码。

方案2：通过PlatformChannel调用原生iOS代码处理光标 #

在iOS原生侧监听并处理鼠标光标切换：

1. Flutter侧定义PlatformChannel：

const platform = MethodChannel('com.app.cursor');

void setClickCursor() async {
  try {
    await platform.invokeMethod('setCursor', {'type': 'click'});
  } on PlatformException catch (e) {
    print("光标设置失败: ${e.message}");
  }
}

void resetCursor() async {
  try {
    await platform.invokeMethod('setCursor', {'type': 'default'});
  } on PlatformException catch (e) {
    print("光标重置失败: ${e.message}");
  }
}

2. iOS原生AppDelegate中实现方法：

#import <Flutter/Flutter.h>
#import <UIKit/UIKit.h>

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  FlutterViewController* controller = (FlutterViewController*)self.window.rootViewController;
  FlutterMethodChannel* channel = [FlutterMethodChannel methodChannelWithName:@"com.app.cursor" binaryMessenger:controller.binaryMessenger];
  
  __weak typeof(self) weakSelf = self;
  [channel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
    if ([@"setCursor" isEqualToString:call.method]) {
      NSString* type = call.arguments[@"type"];
      if ([@"click" isEqualToString:type]) {
        [weakSelf setCursor:[NSCursor pointingHandCursor]];
      } else {
        [weakSelf setCursor:[NSCursor arrowCursor]];
      }
      result(nil);
    } else {
      result(FlutterMethodNotImplemented);
    }
  }];
  
  return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

- (void)setCursor:(NSCursor*)cursor {
  if (@available(macOS 11.0, *)) {
    [NSCursor setCurrentSystemCursor:cursor];
  }
}

@end

之后在Flutter的MouseRegion或按钮组件的悬停/离开回调中调用上述方法即可。

方案3：自定义兼容型按钮组件 #

封装一个通用按钮组件，内置光标切换逻辑，直接替换项目中原有的按钮：

class CompatibleHoverButton extends StatelessWidget {
  final VoidCallback onPressed;
  final Widget child;

  const CompatibleHoverButton({super.key, required this.onPressed, required this.child});

  @override
  Widget build(BuildContext context) {
    return Listener(
      onPointerHover: (_) => SystemMouseCursor.click.applyOverlay(),
      onPointerExit: (_) => SystemMouseCursor.basic.applyOverlay(),
      child: ElevatedButton(
        onPressed: onPressed,
        child: child,
      ),
    );
  }
}

内容的提问来源于stack exchange，提问作者scott1055