如何在Scaffold中更改appBar的大小

Question

当我们返回脚手架时如何更改应用栏大小？

我无法将Scaffold更改为MaterialApp或其他东西

我的代码：

        return Scaffold(
          appBar: AppBar(
            title: Image(
              image: AssetImage('assets/images/logo.png'),
              height: 70.0,
            ),
            centerTitle: true,
            backgroundColor: Colors.white,
            iconTheme: IconThemeData(color: Color.fromRGBO(9, 133, 46, 100)),     
            actions: <Widget>[
              UserIcon(),
              IconButton(
                icon: Icon(
                  Icons.shopping_cart,
                  color: Color.fromRGBO(9, 133, 46, 100),
                  size: 30.0,
                ),
                onPressed: () {
                  //
                },
              ),
            ],       
          ),
          body: body,
        );