之前遇到的一个小问题，那时候谷歌了半天才找到的解决办法
react-navigation的DrawerNavigator左边的抽屉打不开的问题
const MainScreen = DrawerNavigator({
Home: { screen: HomeScreen },
}, {
drawerWidth: width,
contentComponent: CustomDrawerContentComponent,
// for drawer cofig bug
drawerOpenRoute: 'DrawerOpen',
drawerCloseRoute: 'DrawerClose',
drawerToggleRoute: 'DrawerToggle',
})
