如何使用复选框实现kivy ScrollView？

from kivy.app import App
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.scrollview import ScrollView
from kivy.uix.checkbox import CheckBox

class MyScrollView(ScrollView):
    def __init__(self, **kwargs):
        super(MyScrollView, self).__init__(**kwargs)
        self.orientation = 'vertical'  # 设置滚动视图的方向为垂直

        layout = BoxLayout(orientation='vertical')  # 创建一个垂直方向的布局

        # 创建多个复选框并添加到布局中
        for i in range(10):
            checkbox = CheckBox()
            checkbox.active = False  # 设置复选框默认状态为未选中
            checkbox.size_hint_y = None  # 设置复选框在垂直方向上的尺寸
            checkbox.height = 50  # 设置复选框的高度
            layout.add_widget(checkbox)

        self.add_widget(layout)  # 将布局添加到滚动视图中

class MyApp(App):
    def build(self):
        return MyScrollView()

if __name__ == '__main__':
    MyApp().run()