How to use the react-native-im-easemob.EventEmitter.setCmdMessageDidReceive function in react-native-im-easemob

constructor(props) {
        super(props);

        EventEmitter.setCmdMessageDidReceive(newMsg => {
            this.setState(({message}) => ({message: message + '\n' + JSON.stringify(newMsg)}));
        });
        EventEmitter.setMessageDidReceive(newMsg => {
            this.setState(({message}) => ({message: message + '\n' + JSON.stringify(newMsg)}));
        });
        Client.initWithAppKey(test.appKey);
        this.state = {message: ''}
    }