小编Geo*_*ohn的帖子

从另一个页面启动幻灯片拼图项目时出错。

class PuzzlePage extends StatefulWidget {
    final int rows, columns;

    PuzzlePage({int columns = 3, int rows = 3})
    : columns = columns ?? 3,
    rows = rows ?? 3;

    @override
    _PuzzlePageState createState() => _PuzzlePageState();
    }

    class _PuzzlePageState extends State<PuzzlePage> with 
    WidgetsBindingObserver {

    BuildContext _context;

    @override
    void initState() {
    super.initState();

    }

    @override
    void didChangeDependencies(){
    super.didChangeDependencies();
    // Additional code
    }

    @override
    void deactivate() {
    super.deactivate();
    //this method not called when user press android back button or quit
    print('deactivate');
    }

     @override
     void dispose() …