flutter出现NoSuchMethodError: The getter 'modalBarrierDismissLabel' was called on null解决方法

NoSuchMethodError: The getter 'modalBarrierDismissLabel' was called on null解决方法

问题描述：如果在MaterialApp里调用showCupertinoDialog显示弹出框，可能会遇到这个错误。

原因分析：就是Material主题下Context没有这个Cupertine主题的属性

解决方法：添加GlobalCupertinoLocalizations.delegate，如下代码所示

MaterialApp(
  localizationsDelegates: [
    GlobalCupertinoLocalizations.delegate, //添加这行即可解决问题
    GlobalMaterialLocalizations.delegate,
    GlobalWidgetsLocalizations.delegate,
  ],
)
注意：需要在pubspec.yaml添加localizations依赖，如下：
dependencies:
  flutter_localizations:
    sdk: flutter