React Navigation5.0系列四：Nesting navigators(嵌套导航)

此文章为ReactNavigation导航库5.0版本的第4篇，前几篇系列文章以下： React Navigation5.0系列一：StackNavigator的使用 React Navigation5.0系列二：TabNavigation的使用 React Navigation5.0系列三：Drawer navigation的使用 此前几篇系列文章，主要讲了StackNavigator, TavNavigation以及Drawer Navigation的使用讲解，现实中每每是不一样的导航组件组合进行使用的，本篇文章主要讲解导航的嵌套使用及注意事项。 @[toc]

建立须要的页面

// 设置页面
const SettingsScreen = ({ navigation }) => {
  return (
    <View style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
      <Text>SettingScreen</Text>
      <Button
        title="Go to Details"
        onPress={() => navigation.navigate('Detail')}
      />
    </View>
  )
}
// 首页
const HomeScreen = ({ navigation }) => {
  return (
    <View style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
      <Text>HomeScreen</Text>
      <Button
        title="Go to Details"
        onPress={() => navigation.navigate('Detail')}
      />
    </View>
  )
}
// 详情页
const DetailScreen = ({ navigation }) => {
  return (
    <View style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
      <Text>DetailScreen</Text>
      <Button
        title="Go to Detail Again"
        // onPress={() => navigation.navigate('Detail')}
        onPress={() => navigation.push('Detail')}
      />
      <Button title="Go to Home" onPress={() => navigation.navigate('Home')} />
      <Button title="Go back" onPress={() => navigation.goBack()} />
      <Button
        title="Go back to first screen in stack"
        onPress={() => navigation.popToTop()}
      />
    </View>
  )
}

建立三个对应的导航器实例

const Tab = createBottomTabNavigator(); // 选项卡页签tab navigator 实例
const RootStack = createStackNavigator(); // 堆栈stack 实例
const Drawer = createDrawerNavigator(); //  抽屉drawer实例

建立底部导航路由，采用系列二文章代码

function IconWithBadge({ icon, badgeCount, size }) {
  return (
    <View style={{ width: 24, height: 24, margin: 5 }}>
      <Image source={icon} style={{
        width: size,
        height: size
      }} />
      {badgeCount > 0 && (
        <View
          style={{
            // On React Native < 0.57 overflow outside of parent will not work on Android, see https://git.io/fhLJ8
            position: 'absolute',
            right: -6,
            top: -3,
            backgroundColor: 'red',
            borderRadius: 6,
            width: 12,
            height: 12,
            justifyContent: 'center',
            alignItems: 'center',
          }}
        >
          <Text style={{ color: 'white', fontSize: 10, fontWeight: 'bold' }}>
            {badgeCount}
          </Text>
        </View>
      )}
    </View>
  );
}
function HomeIconWithBadge(props) {
  // You should pass down the badgeCount in some other ways like React Context API, Redux, MobX or event emitters.
  return <IconWithBadge {...props} badgeCount={3} />;
}

const TabScreen = () => {
  return (
    <Tab.Navigator 
    headerMode='none' 
    screenOptions={({ route }) => ({
      tabBarIcon: ({ focused, color, size }) => {
        if (route.name === 'Home') {
          return (
            <HomeIconWithBadge
              icon={
                focused
                  ? HomeIconActive
                  : HomeIconNormal
              }
              size={size}
              color={color}
            />
          );
        } else if (route.name === 'Settings') {
          return (
            <Image
              source={focused ? WorkIconActive : WorkIconNormal}
              style={{width: size, height: size}}
            />
          );
        }
      },
    })}
    tabBarOptions={{
      activeTintColor: 'tomato',
      inactiveTintColor: 'gray',
    }}
    >
      <Tab.Screen name="Home" component={HomeScreen} />
      <Tab.Screen name="Settings" component={SettingsScreen} />
    </Tab.Navigator>
  )
}

堆栈(Stack)与Tab嵌套

const rootRouteScreen = () => {
  return (<RootStack.Navigator initialRouteName={'TabNav'}>
          <RootStack.Screen name='TabNav' component={TabScreen} />
          <RootStack.Screen name="Detail" component={DetailScreen} />
         </RootStack.Navigator>
  )
}

Stack Navigator, Tab Navigator与Drawer Navigator综合嵌套

const App = () => {
  return (
    <NavigationContainer>
      <Drawer.Navigator initialRouteName="Home"
        drawerType='slide'
        drawerContent={(props) => <CustomDrawerContent {...props} />}
      >
        <Drawer.Screen name='root' component={rootRouteScreen} />
        <Drawer.Screen name='Setting' component={SettingsScreen} />
      </Drawer.Navigator>
    </NavigationContainer>
  );
}

最后咱们来看一下效果 (type-bilibili)(url-https://player.bilibili.com/player.html?aid=625504500)(image-https://ss.csdn.net/p?http://i2.hdslb.com/bfs/archive/23d0e36df0378cbd3a16ab49d57a746db853648c.jpg)(title-ReactNative官方推荐导航ReactNavigation5.0版导航嵌套)]

传递参数

非嵌套导航使用以下的方式进行传递和接收参数以下方式

// 传递参数
<DrawerItem
        label="Help"
        onPress={() => props.navigation.navigate('Detail',{
          itemId: 86,
          otherParam: 'anything you want here',
        })}
      />
// 接收参数
const DetailScreen = ({ route, navigation }) => {
  const { itemId } = route.params;
  const { otherParam } = route.params;
  return (
    <View style={{ flex: 1, alignItems: 'center', justifyContent: 'center' }}>
      <Text>DetailScreen: {itemId} {otherParam}</Text>
    </View>
  )
}

在嵌套导航中进行参数传递，须要额外加一个params 的key

navigation.navigate('Root', {
  screen: 'Settings',
  params: { user: 'jane' },
});

嵌套导航的最佳实践

建议将嵌套作到最少，应该尝试采用尽量少的嵌套来实现你的业务需求，由于多层嵌套会致使以下几个问题：

• 在多层嵌套的页面，代码难以维护
• 深度嵌套的视图层次结构，这可能会致使低端设备的内存和性能问题
• 嵌套相同类型的导航器（例如，选项卡内的选项卡，抽屉内的抽屉等）让用户的体验极差

其余问题

官网也列举了一下常见的问题，朋友们在集成过程当中遇到问题能够经过以下地址看一下 Troubleshooting, 固然还有Github上的issues 地址：关于React-Navigation的问题

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