我有一个状态数组，状态的值显示在视图中，我还有一个文本视图，我想让文本输入的值改变状态的值，这样状态视图中的值就会改变，但不会改变状态视图中的值， 即如果我输入 a ，视图不会改变，如果我输入 ab ，它会返回一个错误，提示 undefined 不是对象（正在评估 item.toLowerCase） 请问我哪里可能错了

class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      schools: [
        "Abubakar Tafawa Balewa University, Bauchi",
        "Ahmadu Bello University, Zaria",
        "Bayero University, Kano",
      ],
    };
    this.handleChange = this.handleChange.bind(this);
    this.schoolChange = this.schoolChange.bind(this);
  }

  schoolChange(text) {
    for (let i = 0; i < this.state.schools.length; i++) {
      console.log(this.state.schools[i]);
    }
    let c = this.state.schools.map(item => item.toLowerCase(item));
    let b = c.filter(item => item.indexOf(text) > -1);
    let d = b.map(item => item.toUpperCase(item));
    console.log(d);
    var len = d.length;
    for (let i = 0; i < len; i++) {
      let row = d[i];
      this.setState(
        prevState => ({
          schools: [...prevState.schools, row],
        }),
        console.log(this.state.schools[i]),
      );
    }
  }

  handleChange(text) {
    this.setState({ text }, () => {
      this.schoolChange(this.state.text);
    });
  }

  render() {
    const schools = this.state.schools.map((school, index) => (
      <Text style={styles.text}>{school}</Text>
    ));

    return (
      <View>
        <TextInput
          placeholder="Search"
          value={this.state.text}
          onChangeText={text => this.handleChange(text)}
        />
        <ScrollView overScrollMode={"never"} keyboardShouldPersistTaps="always">
          {schools}
        </ScrollView>
      </View>
    );
  }
}