我在React Native中有一个自动滚动的旋转木马,一切都很好,图像每X秒自动滚动一次,也可以手动滚动。
问题是当我离开那个屏幕时,我得到以下错误。
这是我的完整代码... ...
const { width, height } = Dimensions.get("window");
let flatList;
function infiniteScroll(dataList) {
const numberOfData = dataList.length;
let scrollValue = 0,
scrolled = 0;
setInterval(function () {
scrolled++;
if (scrolled < numberOfData) scrollValue = scrollValue + width;
else {
scrollValue = 0;
scrolled = 0;
}
this.flatList.scrollToOffset({ animated: true, offset: scrollValue });
}, 3000);
}
const Carousel = (props) => {
const topTenVideos = useSelector(getTopTenVideos);
const dispatch = useDispatch();
const scrollX = new Animated.Value(0);
let position = Animated.divide(scrollX, width);
const [dataList, setDataList] = useState(topTenVideos);
const isFocused = useIsFocused();
useEffect(() => {
if (isFocused) {
setDataList(topTenVideos);
infiniteScroll(dataList);
}
}, [isFocused]);
const renderRow = (itemData) => {
return (
<CarouselItem
id={itemData.item.id}
img={itemData.item.poster}
title={itemData.item.title}
/>
);
};
return (
<View style={styles.screen}>
<FlatList
ref={(flatList) => {
this.flatList = flatList;
}}
horizontal
data={dataList}
pagingEnabled
scrollEnabled
snapToAlignment="center"
scrollEventThrottle={16}
decelerationRate={"fast"}
showsHorizontalScrollIndicator={false}
onScroll={Animated.event([
{ nativeEvent: { contentOffset: { x: scrollX } } },
])}
keyExtractor={(item, index) => "key" + index}
renderItem={renderRow}
/>
<View style={styles.dotView}>
{dataList.map((_, i) => {
let opacity = position.interpolate({
inputRange: [i - 1, i, i + 1],
outputRange: [0.3, 1, 0.3],
extrapolate: "clamp",
});
return (
<Animated.View
key={i}
style={{
opacity,
height: 8,
width: 8,
borderRadius: 6,
backgroundColor: "white",
margin: 8,
}}
/>
);
})}
</View>
</View>
);
};
它在抱怨这一行 this.flatList.scrollToOffset({ animated: true, offset: scrollValue }); }, 3000)。 这是在我的 无限滚动 函数。
看起来,当屏幕失去焦点时,它仍然在搜索this.flatList.scrollToOffset。
You are not creating your ref properly
,你必须使用 useRef
钩子,如果你使用的是功能组件或 createRef
在类组件的情况下,用于在你的组件中做参考。
看看这个。
https:/reactjs.orgdocshooks-reference.html#useref
创建您的参考文献,如下所示。
const flatListRef = useRef(null)
<FlatList
ref={flatListRef}
// other props
/>
flatListRef.current.scrollToOffset({ animated: true, offset: scrollValue }) // access like this.