React-Native：AsyncStorage.getItem无法正常工作。我已经从react-native-community安装了AsyncStorage

Question

我有一个带有按钮的屏幕，用于选择游戏的玩家人数。单击这些按钮中的任何一个都会调用一个函数，将适当的数字传递给该函数，将该数字存储在异步存储中，然后导航到下一个屏幕。参见下面的代码：

//Example of the buttons:
<Text style={styles.text}>
  How Many Players?
</Text>
<PrimaryButton
  onPress={() => this.startRound(3)}
  label="3"
>
</PrimaryButton>
<PrimaryButton
  onPress={() => this.startRound(4)}
  label="4"
>
</PrimaryButton>

//The function:
startRound = (num_players) => {
  AsyncStorage.setItem('Num_Players', num_players);
  this.props.navigation.navigate('player_names_screen');
}

在下一个屏幕上，如果我尝试使用AsyncStorage.getItem来获取此数字，那么我可以使用它来处理，我只会得到null。参见下面的代码：

constructor (props) {
        super(props);
        this.state = {
            get_players: null
        }
    }

    componentWillMount = () => {
        this.getNumPlayers();
        var players = this.state.get_players;
        alert(players);
    }

    getNumPlayers = async () => {
        let players = await AsyncStorage.getItem('Num_Players');
        this.setState({get_players: players});
    }

我正在使用警报功能来查看我使用AsyncStorage.getItem所获得的结果，并且正如我之前所说，它显示为“ null”。如标题中所述，我已经从react-native-community安装了async-storage，并正在使用“从'@ react-native-community / async-storage';导入AsyncStorage”。

Answer 1

AsyncStorage无法存储整数值，因此将整数值转换为字符串

AsyncStorage.setItem('Num_Players', JSON.stringify(num_players)); 

或

AsyncStorage.setItem('Num_Players', ''+num_players); 

请检查

https://snack.expo.io/@vishal7008/convert-variable-stored-in-asyncstorage-then-state-to-number