使用反应本机元素更改主题不起作用？

我一直在使用 React Native 元素。我想为我的应用程序实现黑暗模式，但由于某种原因我无法获取主题道具<ThemeProvider/>当我的环境中的状态发生变化时发生变化。

这是我的上下文，其中有 darkTheme 和 lightTheme 对象。我也有一个lightThemeState使用 useState 这样我就可以从子组件设置该状态。

import React, { createContext, useState, useEffect } from "react";
import { AsyncStorage } from "react-native";

import { ThemeProvider } from "react-native-elements";
import lightTheme from "../themes/light";
import darkTheme from "../themes/dark";

export const ThemeModeContext = createContext();

export const ThemeContextProvider = (props) => {
  const [lightThemeState, setLightThemeState] = useState(true);

  const saveThemeState = async () => {
    if (lightThemeState) {
      await AsyncStorage.removeItem("lightThemeState");
    } else {
      await AsyncStorage.setItem(
        "lightThemeState",
        JSON.stringify(lightThemeState)
      );
    }
  };

  const getThemeState = async () => {
    currentMode = await AsyncStorage.getItem("lightThemeState");

    if (currentMode) {
      setLightThemeState(JSON.parse(currentMode));
    }
  };

  useEffect(() => {
    saveThemeState();
  }, [lightThemeState]);

  useEffect(() => {
    getThemeState();
  }, []);

  const currentTheme = lightThemeState ? lightTheme : darkTheme;

  console.log("LIGHT THEME STATE", lightThemeState); 
// When I log this after I used the setLigthThemeState in a child component. It gives the correct state ie true or false.
  console.log("COLOR OF THE THEMES BACKGROUND", currentTheme.colors.background);
// This also gives the correct background for the theme that is the "currentTheme" depending on the state. So this far, everything is correct.

  return (
    <ThemeModeContext.Provider value={[lightThemeState, setLightThemeState]}>
      <ThemeProvider theme={currentTheme}>{props.children}</ThemeProvider>
    </ThemeModeContext.Provider>
  );
};

export default ThemeContextProvider;

因为我有另一个用于其他逻辑的上下文。我结合<ThemeContextProvider/>与我的其他背景<JourneyContextProvider/>。就像这样：

import React from "react";
import ThemeContextProvider from "./themeStore";
import JourneyContextProvider from "./journeyStore";

export const CombinedStoreProvider = (props) => {
  return (
    <JourneyContextProvider>
      <ThemeContextProvider>{props.children}</ThemeContextProvider>
    </JourneyContextProvider>
  );
};

export default CombinedStoreProvider;

最后我将整个应用程序包装在我的<CombinedStoreProvider/>。就像这样。

import React from "react";
import { SafeAreaView } from "react-native";

import { createAppContainer, createSwitchNavigator } from "react-navigation";
import { createMaterialBottomTabNavigator } from "react-navigation-material-bottom-tabs";

import Icon from "react-native-vector-icons/Ionicons";

import MoreScreenfrom "./src/screens/MoreModal";
import CombinedStoreProvider from "./store/combinedStore";

const TabNavigator = createMaterialBottomTabNavigator(
  {
    MoreScreen: {
      screen: MoreScreen,
      navigationOptions: {
        title: "More",
        tabBarIcon: ({ tintColor }) => (
          <SafeAreaView>
            <Icon style={[{ color: tintColor }]} size={25} name={"ios-more"} />
          </SafeAreaView>
        ),
      },
    },
  },
  {
    theme: ({ darkTheme }) => console.log(darkTheme),
    barStyleDark: {
      backgroundColor: darkTheme.colors.background,
    },
    barStyleLight: {
      backgroundColor: lightTheme.colors.background,
    },
    shifting: false,
    labeled: true,
    initialRouteName: "MoreScreen",
    activeColor: "#E4DC93",
    inactiveColor: "#fff",
    barStyle: { backgroundColor: "transparent", height: 80, paddingTop: 10 },
  }
);

const AllRoutes = createSwitchNavigator(
  {
    PersonalSettings: {
      title: "Personal Settings",
      screen: PersonalSettings,
      header: ({ goBack }) => ({
        left: (
          <Icon
            name={"chevron-left"}
            onPress={() => {
              goBack();
            }}
          />
        ),
      }),
    },
    Tabs: {
      screen: TabNavigator,
    },
  },
  {
    initialRouteName: "Tabs",
  }
);

const AppContainer = createAppContainer(AllRoutes);

export default App = () => {
  return (
    <CombinedStoreProvider>
      <AppContainer />
    </CombinedStoreProvider>
  );
};

这是我的子组件，我在其中切换lightThemeState在我的背景下。但即使一切看起来都很棒ThemeContextProvider（我控制台记录状态和背景颜色，他们已成功更改主题）。但在这个组件中我只得到了前一个主题。即使当我切换该子组件时，该子组件会重新呈现，但就像什么都没有改变一样lightThemeState。我知道这一点是因为在我切换主题后，控制台再次登录该组件，但日志显示以前的主题颜色。这是子组件：

import React, { useContext, useState } from "react";
import { StyleSheet, View, Text } from "react-native";
import { LayoutView, ContainerView } from "../../components/styles";
import { ThemeModeContext } from "../../../store/themeStore";
import { Card, ListItem, Avatar, ThemeContext } from "react-native-elements";

import CustomButton from "../../components/CustomButton";

const INITIAL_PERSONAL_INFO_STATE = {
  name: "",
  username: "",
  profileImage: "",
  favoriteDestinations: [],
};

const MoreModal = (props) => {
  const [personalInfo, setPersonalInfo] = useState(INITIAL_PERSONAL_INFO_STATE);

  const [lightThemeState, setLightThemeState] = useContext(ThemeModeContext);
  const { theme } = useContext(ThemeContext);
  const { navigate } = props.navigation;

  const primaryColor = theme.colors.background;

  console.log("COLOR IN COMPONENT", primaryColor);
// The color is from the previous theme and even thou the state has changed in the state below
  console.log("LIGHT THEME STATE IN COMPONENT", lightThemeState);

  return (
    <LayoutView primaryColor={theme.colors.background}>
      <ContainerView>
        <View>
        </View>
        <Card
          title={"Settings"}
        >
          <ListItem
            title="Light mode"
            switch={{
              value: lightThemeState,
              onValueChange: (value) => setLightThemeState(value), 
// Here is where I set lighThemeState to false in my context

            }}
            bottomDivider
        </Card>
      </ContainerView>
      <CustomButton title={"Sign in"}></CustomButton>
    </LayoutView>
  );
};

export default MoreModal;

也许您问的 darkTheme 和 lightTheme 有问题？不，如果我将状态从 true 更改为 false 并重新加载应用程序。有用。 不知怎的，主题没有更新<ThemeProvider theme={currentTheme}/>。有人可以解释为什么吗？

您无法使用 React Native Elements 动态更改主题。不幸的是，这没有在任何地方记录 - 这是很重要的一点，因为大多数 RNE 用户会假设他们可以在运行时动态更改整个主题（嗯，我做到了）。

React Native Elements github 上有几个已解决的问题提到了这一点。 例如这个问题 https://github.com/react-native-elements/react-native-elements/issues/1714（2019 年 1 月）其中一位开发人员表示：

目前这是不可能的。 ThemeProvider 不允许在运行时更改其属性。这是因为对 ThemeProvider 的 props 的更改将触发树下所有组件的重新渲染。

UPDATE: You can动态改变主题，但你必须使用带主题 https://react-native-elements.github.io/react-native-elements/docs/customization.html#using-the-theme-in-your-own-componentsReact Native Elements 提供的 HOC（例如调用 withTheme 提供的 updateTheme 函数）。有一点额外的接线，但这是可行的。您可以将 HOC 包装在顶层附近，以便主题更新传播到所有子级。