APP比较多页面时，业务需要从页面A跳转到页面B。
首先定义一个页面receive，另一个页面index，点击index上的按钮，跳转到receive页面。
receive.kv定义如下：
<ReceivePage>:BoxLayout:id:receive_boxorientation:"vertical"canvas.before:Rectangle:pos:self.possize:self.sizesource:"image/l115.jpg"Label:id:receive_tiptext:"receive is ready"color:1,0,0,1Label:id:statuscolor:0,0,0,1Label:id:receive_infocolor:0,0,0,1Button:text:"receive"size_hint:.2,.15pos_hint:{'center_x':0.5,'y':0.1}background_color:1,0.305,0,1
定义reveive.py加载receive.kv
from kivy.uix.boxlayout import BoxLayoutclass ReceivePage(BoxLayout):def __init__(self,**kwargs):