class TestClass extends PureComponent<Props> {
    private leftFilterFlatListRef = null;
    private rightFilterFlatListRef = null;

    private setLeftFilterFlatListRef = ref => {
        this.leftFilterFlatListRef = ref;
    };
    private setRightFilterFlatListRef = ref => {
        this.rightFilterFlatListRef = ref;
    };
    private onRightFilterGroupItemTitleClickInner = index => {
        this.rightFilterFlatListRef &&
            this.rightFilterFlatListRef.scrollToIndex({
                animated: true,
                index,
                viewPosition: 0
            });
    };
    private onLeftFilterItemClickInner = index => {
        console.log('======context====' + JSON.stringify(this.rightFilterFlatListRef.scrollToIndex)); // undefined
        this.rightFilterFlatListRef &&
            this.rightFilterFlatListRef.scrollToIndex({
                animated: true,
                index,
                viewPosition: 0
            });
    };
    public leftFilterScrollTo = index => {
        this.leftFilterFlatListRef &&
            this.leftFilterFlatListRef.scrollToIndex({
                animated: true,
                index: index,
                viewPosition: 1
            });
    };
    public rightFilterScrollTo = index => {
        this.rightFilterFlatListRef &&
            this.rightFilterFlatListRef.scrollToIndex({
                animated: true,
                index,
                viewPosition: 0
            });
    };

    private renderLeftFilterItem = () => {
        return <LeftItemComponent item={item} index={index} onLeftFilterItemClick={this.onLeftFilterItemClickInner} />;
    };

    private renderRightFilterItem = () => {
        return (
            <RightItemComponent
                index={index}
                item={item}
                onRightFilterGroupItemTitleClick={this.onRightFilterGroupItemTitleClickInner}
            />
        );
    };
    private renderLeftFlatItem = ({ item, index }) => {
        return this.renderLeftFilterItem(this.props, item, index, this.props.onVisible);
    };
    private renderRightFlatItem = ({ item, index }) => {
        return this.renderRightFilterItem(this.props, item, index, this.props.onVisible);
    };

    render(): React.ReactNode {
        const { leftFilterData, rightFilterData } = this.props;
        const nonNullLeftFilterData = leftFilterData || [];
        const nonNullRightFilterData = rightFilterData || [];
        return (
            <View>
                <FlatList
                    data={nonNullLeftFilterData}
                    ref={this.setLeftFilterFlatListRef}
                    renderItem={this.renderLeftFlatItem}
                />
                <FlatList
                    data={nonNullRightFilterData}
                    ref={this.setRightFilterFlatListRef}
                    renderItem={this.renderRightFlatItem}
                />
            </View>
        );
    }
}

我收到错误消息
类型错误：undefined不是函数（靠近...“this._scrollRef.scrollTo ...”）
当我把TestClass放到一个FlatList或者ScrollView里面的时候，我发现从FlatList得到的Ref.scrollToIndex是未定义的，但是我想得到scrollToIndex函数，并且应该正确的执行。