How to implement swipe to previous page in Flutter?

correct way is :

MaterialApp(
  .
  .
  .
  theme: ThemeData(
    pageTransitionsTheme: PageTransitionsTheme(
      builders: {
        TargetPlatform.android: CupertinoPageTransitionsBuilder(),
        TargetPlatform.iOS: CupertinoPageTransitionsBuilder(),
      }
    )
  ),
  .
  .
  .
);

Use CupertinoPageRoute to make it work on Android.