React Native - 异常'-[NSNull length]：在调用multiSet时抛出无法识别的选择器发送到实例0x1e6c059b0'答案

【问题标题】：React Native - Exception '-[NSNull length]: unrecognized selector sent to instance 0x1e6c059b0' was thrown while invoking multiSet onReact Native - 异常'-[NSNull length]：在调用multiSet时抛出无法识别的选择器发送到实例0x1e6c059b0'
【发布时间】：2018-11-30 06:05:17
【问题描述】：

我在应用程序加载几秒钟后收到此错误（但有时在几分钟或几次下载后并不总是如此）。我需要解决这个问题。
如果需要更多细节和/或编辑 - 请告诉我，我会做的。

Exception '-[NSNull length]: unrecognized selector sent to instance 0x1e6c059b0' 在使用参数（ ( ( "@Ye-Music:songs", “” ) ), 483 )

AsyncStorage 的功能：

allSongs = () => {
    console.log('hello function!');
    fetch(URL + "/SongsList", {
      body: null,  //// sending null because its a view from SQL db
      method: "POST",
      headers: {
        Accept: 'application/json',
        "Content-type": "application/json; charset=UTF-8"
      }
    })
      .then(res => { return res.json()})
      .then((songsResult) => {
        AsyncStorage.setItem("@Ye-Music:songs", songsResult.d);
      })
      .catch(err => {
        console.error(err);
      });
  };

包.json

"dependencies": {
    "@expo/samples": "2.1.1",
    "expo": "29.0.0",
    "react": "16.3.1",
    "react-native": "https://github.com/expo/react-native/archive/sdk-29.0.0.tar.gz",
    "react-native-elements": "^0.19.1",
    "react-native-material-cards": "^1.0.9",
    "react-native-music-control": "^0.7.3",
    "react-native-music-player-service": "^0.1.4-beta",
    "react-native-search-header": "^0.3.0",
    "react-native-sound": "^0.10.9",
    "react-native-track-player": "^0.2.5",
    "react-navigation": "^2.9.3"
},

【问题讨论】：

标签： react-native exception exception-handling asyncstorage

【解决方案1】：

调用AsyncStorage时，需要定义值。如果不是，您将收到您遇到的错误。

错误处理逻辑（对于未定义的情况）可能是最好的方法。

if(songsResult && songsResult.d) {
   AsyncStorage.setItem("@Ye-Music:songs", songsResult.d);
} else {
   // handle error case here
}

【讨论】：

【解决方案2】：

确保songsResult.d 不是未定义的并且是长度> 0 的字符串！

【讨论】：