React-Native滚动到索引不起作用

Question

在我的应用程序中，ScrollToIndex无法按预期工作。这是我的代码。

  getItemLayout = (data, index) => (
    { length: 50, offset: 50 * index, index }
  )

  scrollToIndex = () => {
       if(this.flatListRef != null){
            setTimeout(() => this.flatListRef.scrollToIndex({animated: false, index: 5}), 200)
        }
    // this.flatListRef.scrollToIndex({animated: true, index: 5});
  }


  // render post
  renderPost({ item, index }) {
    return (
      <Post
        post={item} 
        likeIsLoading={
          item.shareId === this.props.likeLoadingPostId &&
          this.props.likeIsLoading
        }
        likeCount={item.likeCount > 0 ? item.likeCount : ""}
        likeIcon={item.hasLiked === 1 ? LikeActive : LikeInactive}
        name={item.hasLiked === 1 ? "like-active" : "like-inactive"}
        onIconClick={payload => this.onIconClick(payload)}
      />
    );
  }

  // render
  render() {
    let { posts, featuredWorkouts, mainFeedIsLoading } = this.props;

    let mainFeedData = (
      <View>
        <View style={{ marginBottom: 5 }}>
          <SwiperContainer featuredWorkouts={featuredWorkouts} />
        </View>

        <FlatList
          ref={(ref) => { this.flatListRef = ref; }}
          data={posts}
          extraData={[posts, mainFeedIsLoading, featuredWorkoutsAreLoading]}
          renderItem={(item, index) => this.renderPost(item, item.shareId)}
          getItemLayout={this.getItemLayout}
          // initialScrollIndex={4}
          keyExtractor={item => item.shareId}
        />
      </View>
    );

    if (mainFeedIsLoading) {
      mainFeedData = (
        <View style={styles.screenLoader}>
          <ScreenLoader color="lightblue" size="large" />
        </View>
      );
    }

    return (
      <View>
         <Button
            onPress={() => this.scrollToIndex()}
            title="Tap to scrollToIndex"
            color="darkblue"
          />
        <ScrollView>{mainFeedData}</ScrollView>
      </View>
    );
  }

我尝试了在互联网上提出的建议，但没有一个有效。我在这做错了什么？我怎样才能实现我的目标？例如，我想在单击按钮时移动到第5个索引。