问缺少回收视图小部件

EN

from kivy.app import App
from kivy.lang import Builder
from kivy.core.window import Window
from kivy.uix.recycleview import RecycleView
from kivy.uix.boxlayout import BoxLayout

Window.size = (350, 600)

Builder.load_string('''
<MyLayout>:
    BoxLayout:
        orientation: "vertical"
        spacing: 10
        padding: 10

        Label :
            text : 'Favourite Pizza'
           
        TextInput :
            font_size: 30
            focus: True
            multiline : False
           
        <RV>:    
            RecycleBoxLayout:   
                viewclass: 'TextInput'        
                default_size: None, 30
                default_size_hint: 1, None
                size_hint_y: .8
                height: self.minimum_height
                orientation : 'vertical'  
                  
''')

class MyLayout(BoxLayout):
    pass

class RV(RecycleView):  
    def __init__(self, **kwrgs):
        super(RV, self).__init__(**kwrgs)
        content = ["Pepperoni", "Cheese","Papper", "Hawaii", "Seafood", 
        "Ham", "Taco", "Onion"]
        self.data = [{'text':item} for item in content]     
        print(content)

class MainApp(App):
    title='Search App'
    def build(self):
        Window.clearcolor = (51/255, 153/255, 1, 1) 
        return MyLayout()    
   
MainApp().run()