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javascript - 如何访问 react-native-maps 中的坐标？

问题描述

我正在尝试通过使用 react-native-maps 中的“coords”道具在我的 react native 应用程序中使用用户的当前位置。

问题是当我尝试 console.log currentLocation.coords 时出现错误：

TypeError: null is not an object (evaluating 'currentLocation.coords')

但是当我 console.log currentLocation 时，我可以在响应中看到 coords 道具。

Object {
  "coords": Object {
    "accuracy": 5,
    "altitude": 5,
    "altitudeAccuracy": 5,
    "heading": 0,
    "latitude": 13.184791,
    "longtitude": 55.735991,
    "speed": 0,
  },
  "timestamp": 1000000,
}

const locationReducer = (state, action) => {
    switch (action.type) {
        case 'add_current_location':
            return { ...state, currentLocation: action.payload }
        default:
            return state;
    }
};

const startRecording = dispatch => () => {};
const stopRecording = dispatch => () => {};
const addLocation = dispatch => (location) => {
    dispatch({ type: 'add_current_location', payload: location })
};

export const { Context, Provider } = createDataContext(
    locationReducer,
   { startRecording, stopRecording, addLocation },
   { recording: false, locations: [], currentLocation: null }
);

const Map = () => {
    const { state: { currentLocation } } = useContext(LocationContext);

    console.log(currentLocation.coords);

    if (!currentLocation) {
        return <ActivityIndicator size="large" style={{ marginTop: 200 }} />;
    };

    return (
        <MapView
            style={styles.map}
            initialRegion={{
                ...currentLocation.coords,
                latitudeDelta: 0.01,
                longitudeDelta: 0.01
            }}
        >
        </MapView>
    );
};

const TrackCreateScreen = () => {
    const { addLocation } = useContext(LocationContext);
    const [err, setErr] = useState(null);

    const startWatching = async () => {
        try {
            await requestPermissionsAsync();
            await watchPositionAsync({
                accuracy: Accuracy.BestForNavigation,
                timeInterval: 1000,
                distanceInterval: 10
            }, (location) => {
                addLocation(location);
            });
        } catch (e) {
            setErr(e);
        }
    };

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

如何访问坐标？（我需要使用经度和纬度）

标签： javascriptreactjsreact-native

解决方案

我使用“react-native-location”来获取用户的当前位置。在subscribeToLocationUpdates中，我正在获取纬度和经度，如下所示。

 let requestBody = await getPlaceNameFromLocation(locations[0].latitude, locations[0].longitude)

如您所见，我正在获取在您的情况下可能存在问题的位置数组。请检查。因为数组也是对象。

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