这是我的地图视图的外观：
<MapView
style={styles.mapStyle}
initialRegion={{
latitude: 51.524300,
longitude: -0.037790,
latitudeDelta: 0.0122,
longitudeDelta: 0.0421,
}}
>
<Marker
coordinate={{
latitude:51.524464,
longitude:-0.036285,
latitudeDelta:0.0,
longitudeDelta:0.0
}}
title={"Marker 1"}
description={customData.text1}
/>
<Marker
coordinate={{
latitude:51.524310,
longitude:-0.037798,
latitudeDelta:0.0,
longitudeDelta:0.0
}}
title={"Marker 2"}
description={customData.text2}
/>
<Marker
coordinate={{
latitude:51.523174,
longitude:-0.039332,
latitudeDelta:0.0,
longitudeDelta:0.0
}}
title={"Marker 3"}
description={customData.text3}
/>
</MapView>
如您所见，我已经对3个标记进行了硬编码，只是为了确保MapViews正常工作。现在，我使用一个外部API，该API根据用户的输入告诉停车位。因此，例如，如果用户输入某个邮政编码/邮政编码，则api返回一个数组，其中包含有关停车位的各种信息，例如经度和纬度。我想在地图上用标记表示这些停车位。我为此使用FlatList：
<FlatList
data = {parkingSpaces}
renderItem={({ item }) => {
return <MapView.Marker
coordinate={{
latitude: parseInt(item.latitude),
longitude:parseInt(item.longitude)
}}
title = {"parking markers"}
/>
}}
keyExtractor={item => item.unique_identifier}
/>
我没有任何错误，但是我看不到地图上的标记。下面是我的完整代码
import React ,{Component,useState,useEffect} from 'react'
import {View,Text,StyleSheet,Dimensions,Button,Alert,FlatList} from 'react-native'
import MapView , {Marker}from 'react-native-maps'
import axios from 'axios'
import { TextInput } from 'react-native-gesture-handler'
import camdenParking from '../api/camdenParking'
import SearchBar from '../components/SearchBar'
/// Key Secret : 5ulg30lagu2o493uwsmn24rxklsg0ivb05k2zl6xqhiz8js9e7
/// App Secret Token : NTEX14nQLbrS8MIz4RmC6riUV6K2aQ_j687H
const HomeScreen = ()=>
{
const [parkingSpaces,setparkingSpaces] = useState([])
const[term,setTerm] = useState('')
let userLatitude = 0
let userLongitude = 0
const customData = require("./MarkersText.json")
const searchApi = async() => {
const response = await camdenParking.get("",{
params:{
//longitude:-0.115444,
//latitude:51.517597
postcode: term
}
}) // you can change this later on
console.log(response.data)
setparkingSpaces(response.data)
console.log(term)
}
const findCoordinates = () => {
navigator.geolocation.getCurrentPosition(
position => {
const locationString = JSON.stringify(position); // Here we get the JSON object but it needs to be parsed
var longLat = JSON.parse(locationString); // Here we parse the JSON object
userLatitude=longLat.coords.latitude
userLongitude=longLat.coords.longitude
console.log(userLatitude) // This prints the current latitude from the user
console.log(userLongitude) // This prints the longitude
},
error => Alert.alert(error.message),
{ enableHighAccuracy: false, timeout: 20000, maximumAge: 1000 }
);
};
//useEffect(()=>{
// searchApi()
//},[])
return(
<View style={styles.container}>
<SearchBar
term={term}
onTermChange={newTerm=>setTerm(newTerm)}
onTermSubmit={()=> searchApi(term)}
/>
<MapView
style={styles.mapStyle}
initialRegion={{
latitude: 51.524300,
longitude: -0.037790,
latitudeDelta: 0.0122,
longitudeDelta: 0.0421,
}}
>
<Marker
coordinate={{
latitude:51.524464,
longitude:-0.036285,
latitudeDelta:0.0,
longitudeDelta:0.0
}}
title={"Marker 1"}
description={customData.text1}
/>
<Marker
coordinate={{
latitude:51.524310,
longitude:-0.037798,
latitudeDelta:0.0,
longitudeDelta:0.0
}}
title={"Marker 2"}
description={customData.text2}
/>
<Marker
coordinate={{
latitude:51.523174,
longitude:-0.039332,
latitudeDelta:0.0,
longitudeDelta:0.0
}}
title={"Marker 3"}
description={customData.text3}
/>
</MapView>
<Text>We have found {parkingSpaces.length} results</Text>
<Button onPress={searchApi} title=" Click Here To Get Parking Spaces" />
<Button onPress={findCoordinates} title=" Click Here To Get User's Location" />
<Text>Parking Spaces found around {term}</Text>
<FlatList
data = {parkingSpaces}
renderItem={({ item }) => {
return <MapView.Marker
coordinate={{
latitude: parseInt(item.latitude),
longitude:parseInt(item.longitude)
}}
title = {"parking markers"}
/>
}}
keyExtractor={item => item.unique_identifier}
/>
<FlatList
data = {parkingSpaces}
renderItem={({ item }) => {
return <Text> {item.road_name} | Possible Available Spaces:{item.parking_spaces} </Text>
}}
keyExtractor={item => item.unique_identifier}
/>
</View>
);
};
const styles = StyleSheet.create(
{
container:{
flex:1,
backgroundColor: '#fff',
//alignItems: 'center',
//justifyContent: 'center',
//...StyleSheet.absoluteFillObject,
//marginLeft:0,
//height:400,
//width:400,
//justifyContent:"flex-end",
//alignItems:"center",
},
mapStyle: {
width: 400,
height:400,
//width: Dimensions.get('window').width,
//height: Dimensions.get('window').height,
},
}
)
export default HomeScreen
更新
这是我的代码现在的样子：
import React ,{Component,useState,useEffect} from 'react'
import {View,Text,StyleSheet,Dimensions,Button,Alert,FlatList} from 'react-native'
import MapView , {Marker}from 'react-native-maps'
import axios from 'axios'
import { TextInput } from 'react-native-gesture-handler'
import camdenParking from '../api/camdenParking'
import SearchBar from '../components/SearchBar'
/// Key Secret : 5ulg30lagu2o493uwsmn24rxklsg0ivb05k2zl6xqhiz8js9e7
/// App Secret Token : NTEX14nQLbrS8MIz4RmC6riUV6K2aQ_j687H
const HomeScreen = ()=>
{
const [parkingSpaces,setparkingSpaces] = useState([])
const[term,setTerm] = useState('')
let userLatitude = 0
let userLongitude = 0
const customData = require("./MarkersText.json")
const searchApi = async() => {
const response = await camdenParking.get("",{
params:{
//longitude:-0.115444,
//latitude:51.517597
postcode: term
}
}) // you can change this later on
console.log(response.data)
setparkingSpaces(response.data)
console.log(term)
}
const findCoordinates = () => {
navigator.geolocation.getCurrentPosition(
position => {
const locationString = JSON.stringify(position); // Here we get the JSON object but it needs to be parsed
var longLat = JSON.parse(locationString); // Here we parse the JSON object
userLatitude=longLat.coords.latitude
userLongitude=longLat.coords.longitude
console.log(userLatitude) // This prints the current latitude from the user
console.log(userLongitude) // This prints the longitude
},
error => Alert.alert(error.message),
{ enableHighAccuracy: false, timeout: 20000, maximumAge: 1000 }
);
};
//useEffect(()=>{
// searchApi()
//},[])
return(
<View style={styles.container}>
<SearchBar
term={term}
onTermChange={newTerm=>setTerm(newTerm)}
onTermSubmit={()=> searchApi(term)}
/>
<MapView
style={styles.mapStyle}
initialRegion={{
latitude: 51.524300,
longitude: -0.037790,
latitudeDelta: 0.0122,
longitudeDelta: 0.0421,
}}
>
{parkingSpaces.map((val, index) => {
return (<MapView.Marker
coordinate={{
latitude: parseInt(val.latitude),
longitude:parseInt(val.longitude)
}}
key={index}
title = {"parking markers"}
/>);
})}
</MapView>
<Text>We have found {parkingSpaces.length} results</Text>
<Button onPress={searchApi} title=" Click Here To Get Parking Spaces" />
<Button onPress={findCoordinates} title=" Click Here To Get User's Location" />
<Text> WC2A 3PD</Text>
<Text>Parking Spaces found around {term}</Text>
<FlatList
data = {parkingSpaces}
renderItem={({ item }) => {
return <MapView.Marker
coordinate={{
latitude: parseInt(item.latitude),
longitude:parseInt(item.longitude),
latitudeDelta:0.0,
longitudeDelta:0.0
}}
title = {"parking markers"}
description = {"parking"}
/>
}}
keyExtractor={item => item.unique_identifier}
/>
<FlatList
data = {parkingSpaces}
renderItem={({ item }) => {
return <Text> {item.road_name} | Possible Available Spaces:{item.parking_spaces} </Text>
}}
keyExtractor={item => item.unique_identifier}
/>
</View>
);
};
const styles = StyleSheet.create(
{
container:{
flex:1,
backgroundColor: '#fff',
//alignItems: 'center',
//justifyContent: 'center',
//...StyleSheet.absoluteFillObject,
//marginLeft:0,
//height:400,
//width:400,
//justifyContent:"flex-end",
//alignItems:"center",
},
mapStyle: {
width: 400,
height:400,
//width: Dimensions.get('window').width,
//height: Dimensions.get('window').height,
},
}
)
export default HomeScreen
答案 0 :(得分：1)
第一个问题是使用FlatList作为标记的容器。解决方案是在MapView之间的parkingSpaces数组上进行映射。第二个问题是您在坐标上调用parseInt，这将导致地图根本不渲染标记。另外，您将失去精度。
代码：
<MapView
style={styles.mapStyle}
initialRegion={{
latitude: 51.524300,
longitude: -0.037790,
latitudeDelta: 0.0122,
longitudeDelta: 0.0421,
}}
>
{parkingSpaces.map((val, index) => {
return (<MapView.Marker
coordinate={{
latitude: val.latitude,
longitude: val.longitude
}}
key={index}
title = {"parking markers"}
/>);
})}
</MapView>
工作演示：