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我正在尝试使用 useEffect 找到 ComponentWillMount 方法的替代品。但是 panresponder 变量不是在初始渲染之前创建的。谁能告诉我我在这里做的任何错误?没有 useEffect,页面将被渲染。手势未被捕获。

      const makeup = () => {
        useEffect(() => {
            console.log('I am about to render!');
            const panResponder = useRef(
              PanResponder.create({
                onStartShouldSetPanResponder: (e, gestureState) => true,
                onPanResponderMove: (e, gestureState) => {....},
                onPanResponderRelease: (e, gestaureState) => {....}
              }));
          },[]);

        return ARTICLES.map((item, i) => {
          console.log("Makeup i:"+i+" item:"+item);
          if (i === index.currentIndex - 1) {
            return (
              <Animated.View
                key={item.id}
                style={swipeCardPosition.getLayout()}
                {...panResponder.panHandlers}
              >
                  
              </Animated.View>
            );
          }
          if (i < index.currentIndex) {
            return null;
          }
          return (
            <Animated.View
              key={item.id}
              style={index.currentIndex === i ? position.getLayout() : null}
              {...(index.currentIndex === i
                ? { ...panResponder.panHandlers }
                : null)}
>
            </Animated.View>
          );
        }).reverse();
      };
[Error on execution][1] [1]: https://i.stack.imgur.com/sls5E.png
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1 回答 1

0

检查官方文档。它描述了如何使用PanResponder功能组件。

例如:

const ExampleComponent = () => {
  const panResponder = React.useRef(
    PanResponder.create({
      onStartShouldSetPanResponder: (e, gestureState) => true,
      onPanResponderMove: (e, gestureState) => {....},
      onPanResponderRelease: (e, gestaureState) => {....}
    })
  ).current;

  return <View {...panResponder.panHandlers} />;
};

由于很多原因,您的示例不起作用,最明显的是因为您不能调用useRefinsideuseEffect

于 2021-02-07T18:10:47.883 回答