嘿，我是 React Native 的新手，目前我正尝试使用来自 API 的数据将数据放入选择器中。我很困惑，它出现了错误，说 TypeError：null 不是对象（评估 this.state.schedules.map）。状态有问题吗，还是我误解了什么概念

这是获取 API

export function getSchedule (token, resultCB) {
    var endpoint = "/api/getList"

    let header = {
        "Content-Type": "application/x-www-form-urlencoded",
        "Authorization": "Bearer " + token
    };

    return dispatch => {
        return fetchAPI(endpoint, 'GET', header)
            .then((json) => {          
                dispatch({ type: t.SCHEDULE, schedules: json.datas.description });
                resultCB(json.schedules)
            })
            .catch((error) => {
                dispatch({ type: types.EMPTY_SCHEDULE });       
                resultCB(error)
            })
    }
}

这是我放置选择器的地方

export const mapStateToProps = state => ({
  token: state.authReducer.token,
  message: state.authReducer.message,
  schedules: state.authReducer.schedules
});

export const mapDispatchToProps = (dispatch) => ({
  actionsAuth: bindActionCreators(authAction, dispatch)
});

class Change extends Component {
    
  constructor(){
        super();
        this.state={
            staffId: "",
            schedule: '',
            type_absen: 1,
            schedules: null
        }

    }
    
componentDidMount(){
    this.props.actionsAuth.getSchedule(this.props.token);
  }
  
  render() {
      return (
  
                  <View style={styles.picker}>
                    <Picker
                    selectedValue={this.state.schedule}
                    style={{backgroundColor:'white'}}
                    onValueChange={(sch) => this.setState({schedule: sch})}>
                    {this.state.schedules.map((l, i) => {
                    return <Picker.Item value={l} label={i} key={i}  /> })} 
                    </Picker>
                  </View>

      );
  }
}
  export default connect(mapStateToProps, mapDispatchToProps)(Change);