如何获取当前导航状态

Question

我正在使用来自 https://reactnavigation.org/docs/navigators/tab 的 React Navigation 的选项卡导航器，当我在选项卡屏幕之间切换时，我在 this.props.navigation 中没有任何导航状态。

标签导航器：

    import React, { Component } from 'react';
    import { View, Text, Image} from 'react-native';
    import DashboardTabScreen from 'FinanceBakerZ/src/components/dashboard/DashboardTabScreen';
    import { TabNavigator } from 'react-navigation';


       render() {
        console.log(this.props.navigation);   

        return (
          <View>
              <DashboardTabNavigator  />
          </View>
        );
      }



    const DashboardTabNavigator = TabNavigator({
      TODAY: {
        screen: DashboardTabScreen
      },
      THISWEEK: {
        screen: DashboardTabScreen
      }
    });

仪表板屏幕：

import React, { Component } from 'react';
import { View, Text} from 'react-native';

export default class DashboardTabScreen extends Component {
  constructor(props) {
    super(props);

    this.state = {};
    console.log('props', props);

  }

  render() {
    console.log('props', this.props);
    return (
      <View style={{flex: 1}}>
        <Text>Checking!</Text>
      </View>
    );
  }
}

当它首先呈现组件时，我在仪表板屏幕上获得了道具，但是当我切换选项卡时我没有得到道具。 我需要获取当前的屏幕名称，即今天或本周。

Answer 1

您的问题与“屏幕跟踪”有关，react-navigation 对此有官方指南。你可以使用onNavigationStateChange 来跟踪屏幕，使用内置的导航容器或者编写一个 Redux 中间件来跟踪屏幕，如果你想与 Redux 集成。更多详细信息可以在官方指南中找到：Screen-Tracking。以下是使用 onNavigationStateChange 的指南中的示例代码：

import { GoogleAnalyticsTracker } from 'react-native-google-analytics-bridge';

const tracker = new GoogleAnalyticsTracker(GA_TRACKING_ID);

// gets the current screen from navigation state
function getCurrentRouteName(navigationState) {
  if (!navigationState) {
    return null;
  }
  const route = navigationState.routes[navigationState.index];
  // dive into nested navigators
  if (route.routes) {
    return getCurrentRouteName(route);
  }
  return route.routeName;
}

const AppNavigator = StackNavigator(AppRouteConfigs);

export default () => (
  <AppNavigator
    onNavigationStateChange={(prevState, currentState) => {
      const currentScreen = getCurrentRouteName(currentState);
      const prevScreen = getCurrentRouteName(prevState);

      if (prevScreen !== currentScreen) {
        // the line below uses the Google Analytics tracker
        // change the tracker here to use other Mobile analytics SDK.
        tracker.trackScreenView(currentScreen);
      }
    }}
  />
);

Answer 2

先检查所有属性，比如

<Text>{JSON.stringify(this.props, null, 2)}</Text>

上面的 json 数组将显示您在 routeName 索引下的当前导航状态，即

this.props.navigation.state.routeName

Answer 3

您是否尝试在路由对象中定义 navigationOptions？

const DashboardTabNavigator = TabNavigator({
  TODAY: {
    screen: DashboardTabScreen
    navigationOptions: {
     title: 'TODAY',
    },
  },
})

您还可以将 navigationOptions 设置为将与导航对象一起调用的回调。

const DashboardTabNavigator = TabNavigator({
  TODAY: {
    screen: DashboardTabScreen
    navigationOptions: ({ navigation }) => ({
     title: 'TODAY',
     navigationState: navigation.state,
    })
  },
})

阅读更多关于 navigationOptions https://reactnavigation.org/docs/navigators/