如何在Kivy中“更新”屏幕上动态创建的按钮

from kivy.app import App
from kivy.uix.button import Button
from kivy.uix.boxlayout import BoxLayout

class MyApp(App):
    def build(self):
        self.layout = BoxLayout(orientation='vertical')
        return self.layout

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

def create_button(self):
    button = Button(text='New Button')
    self.layout.add_widget(button)

def update_button_text(self, button):
    button.text = 'Updated Button'

def build(self):
    self.layout = BoxLayout(orientation='vertical')
    update_button = Button(text='Update Button Text')
    update_button.bind(on_release=lambda button: self.update_button_text(button))
    self.layout.add_widget(update_button)
    return self.layout