首先，感谢您的阅读。我正在使用Expo开发本机。我使用componentWillMount和componentDidmount在我的应用中设置功能。 可以，但是我很难理解为什么我的组件渲染了4次...

我得到这个结果（通过console.log）：

  

结果retrieveDeviceManufacturer（）：42   ===> retrieveProfileUserId 42结果retrieveDeviceUID（）：...结果retrieveDeviceOSVersion（）：10个结果   resolveDeviceManufacturer（）：Google连接类型wifi是   连接的？是

但是我每次执行组件都连续4次。 我当然是本机反应的新手，需要帮助才能完全理解这一点。

非常感谢您的帮助。这是我的整页代码：

export default class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = { isFirstConnection: true };
    status: "0";
    deviceOSVersion: null;
    deviceManufacturer: null;
    deviceUID: null;
    profileUserId: null;
  }

  performTimeConsumingTask = async () => {
    return new Promise(resolve =>
      setTimeout(() => {
        resolve("result");
      },1000)
    );
  };
  componentWillMount = async () => {
    this.setState({ deviceOSVersion: await retrieveDeviceOSVersion() });
    this.setState({ deviceManufacturer: await retrieveDeviceManufacturer() });
    this.setState({ deviceUID: await retrieveDeviceUID() });
    this.setState({ profileUserId: await retrieveProfileUserId() });
  };

  async componentDidmount() {
    this.setState({ status: "6" });
    // Preload data from an external API
    // Preload data using AsyncStorage
    const data = await this.performTimeConsumingTask();

    if (data !== null) {
      this.setState({ isFirstConnection: false });
    }

    Font.loadAsync({
      Roboto: require("./assets/fonts/Roboto-Black.ttf")
    });
  }

  render() {
    if (this.state.status == "6") {
      console.log(
        "Results retrieveDeviceManufacturer() : ",this.state.profileUserId
      );
      if (this.state.profileUserId !== null && this.state.profileUserId > 0) {
        // OK
      } else {
        // Need connection
      }
      console.log("===>retrieveProfileUserId",this.state.profileUserId);

      // Device UUID
      console.log("Results retrieveDeviceUID() : ",this.state.deviceUID);
      if (this.state.deviceUID !== null) {
        // OK
      } else {
        // TODO : next step...
        storeDeviceUID(getDeviceUID());
      }

      // Detect Manufacturer : iOS,Android,..
      if (this.state.deviceManufacturer !== null) {
        // OK
      } else {
        storeDeviceManufacturer(getDeviceManufacturer());
      }

      // Get system version
      if (this.state.deviceOSVersion !== null) {
        // OK
      } else {
        storeDeviceOSVersion(getDeviceOSVersion());
      }

      console.log(
        "Results retrieveDeviceOSVersion() : ",this.state.deviceOSVersion
      );
      console.log(
        "Results retrieveDeviceManufacturer() : ",this.state.deviceManufacturer
      );

      NetInfo.fetch().then(state => {
        console.log("Connection type",state.type);
        console.log("Is connected?",state.isConnected);
      });
      if (this.state.isFirstConnection) {
        return <SplashScreen />;
      }
      return <Navigation />;
    } else {
      console.log("STATUS INITIALISATION");
      this.setState({ status: "1" });
      return null;
    }
  }
}