Child.js：export default class Child extends Component {  testFunc = () => {   console.log("test")  }  componentDidMount() {    this.props.onRef(this) }父.js：export default class Parent extends Component { render() {    return (   <>     <Child onRef = {ref => (this.child=ref)}> </Child>     <Button onPress={this.child.testFunc()}></Button>   </>   ) }}我想知道如何從 React Native 的父組件調(diào)用子組件中的函數(shù)？我嘗試了上面的代碼，我收到錯誤“TypeError undefined is not an object (evaluate '_this.child.testFunc')。當(dāng)我在這里嘗試建議的解決方案時遇到同樣的錯誤：Call child function from parent component in React Native。有人可以幫我嗎？