Flutter | Dark and Light theme using provider

ThemeChanger class extended by ChangeNotifier

class ThemeChanger extends ChangeNotifier {
ThemeData _themeData;
ThemeChanger(this._themeData);
getTheme() => _themeData;
setTheme(ThemeData theme) {
_themeData = theme;
notifyListeners();
}
}

wrap MaterialApp with ChangeNotifierProvider

return ChangeNotifierProvider<ThemeChanger>(
create: (_) => ThemeChanger(lightTheme), child: MaterialAppParent());
}

create instance of Provider<ThemeChanger>

final theme = Provider.of<ThemeChanger>(context);

create a toggle button to switch themes

theme.getTheme() == lightTheme
? IconButton(
icon: Icon(Icons.ac_unit),
onPressed: () {
theme.setTheme(darkTheme);
})
: IconButton(
icon: Icon(Icons.lightbulb_outline),
onPressed: () {
theme.setTheme(lightTheme);
})