最新のreact-nativeでfetchが動かない。 react-native自体のバグだった。

https://q-a-assistant.com/computer-internet-technology/15536_react-native-fetch-throws-undefined-is-not-a-function-evaluating-0-reactnative-fetch.html

に書かれているとおり、

import {} from 'react-native';の中からfetchを抜くと直る。

なんだそれ

>||

import React, { Component } from "react";
import {
Platform,
StyleSheet,
Text,
View,
//fetch,
ActivityIndicator,
ListView
} from "react-native";

export default class MyCourse extends Component<{}> {
constructor(props) {
super(props);
this.state = {
isLoading: true
};
}

async componentDidMount() {
try {
let response = await fetch(
"https://facebook.github.io/react-native/movies.json"
);
let responseJson = await response.json();
let ds = new ListView.DataSource({
rowHasChanged: (r1, r2) => r1 !== r2
});
this.setState(
{
isLoading: false,
dataSource: ds.cloneWithRows(responseJson.movies)
},
function() {
// do something with new state
}
);
//return responseJson.movies;
} catch (error) {
console.error(error);
}
}

render() {
if (this.state.isLoading) {
return (
<View style={{ flex: 1, paddingTop: 20 }}>
<ActivityIndicator />
</View>
);
}

return (
<View style={{ flex: 1, paddingTop: 20 }}>
<ListView
dataSource={this.state.dataSource}
renderRow={rowData => (
<Text>
{rowData.title}, {rowData.releaseYear}
</Text>
)}
/>
</View>
);
}
}

||<

ちなみに試したコードはreact nativeのfetchだった