你应该使用<Circle/>而不是`。下面是一个sample code和代码片段。（注意：lineDashPattern仅适用于iOS（doc）。

import React, { Component } from 'react';
import { Text, View, StyleSheet, Dimensions } from 'react-native';
import MapView, { Marker, Circle, Polyline } from 'react-native-maps';

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
  map: {
    width: Dimensions.get('window').width,
    height: Dimensions.get('window').height,
  },
});

class MapApp extends Component {
  render() {
    return (
      <View style={styles.container}>

        <MapView style={styles.map}
          initialRegion={{
            latitude: 37.78825,
            longitude: -122.4324,
            latitudeDelta: 0.0922,
            longitudeDelta: 0.0421,
          }}
        >
          <Marker
            coordinate={{ latitude: 37.78825, longitude: -122.4324 }}
          />

          <Circle
            center={{ latitude: 37.78825, longitude: -122.4324 }}
            radius={1000}
            strokeWidth={3}
            strokeColor="green"
            lineDashPattern={[10]} />

        </MapView>
      </View>
    );
  }
}

export default MapApp;

ios和android支持折线描边

使用linedashpattern

代码：

<Polyline
    coordinates={[
        { latitude: 37.8025259, longitude: -122.4351431 },
        { latitude: 37.7896386, longitude: -122.421646 },
        { latitude: 37.7665248, longitude: -122.4161628 },
        { latitude: 37.7734153, longitude: -122.4577787 },
        { latitude: 37.7948605, longitude: -122.4596065 },
        // { latitude: 37.8025259, longitude: -122.4351431 }
    ]}
lineDashPattern={[5, 5,5,5,5]}
    strokeColor="yellow" // fallback for when `strokeColors` is not supported by the map-provider
    strokeColors={[
        '#7F0000',
        '#00000000', // no color, creates a "long" gradient between the previous and next coordinate
        '#B24112',
        '#E5845C',
        '#238C23',
        // '#7F0000'
    ]}
    strokeWidth={5}
/>