How to use the iview.Form.Item function in iview

// 按需引入iview组件
import { Card, Timeline, Menu, Icon, Progress, Button, Form, Input, Message } from "iview";
import { Row, Col } from "iview/src/components/grid";
Vue.component("Card", Card);
Vue.component("Timeline", Timeline);
Vue.component("MenuItem", Menu.Item);
Vue.component("Menu", Menu);
Vue.component("Row", Row);
Vue.component("Col", Col);
Vue.component("Icon", Icon);
Vue.component("Button", Button);
Vue.component("TimelineItem", Timeline.Item);
Vue.component("Progress", Progress);
Vue.component("Form", Form);
Vue.component("FormItem", Form.Item);
Vue.component("Input", Input);
Vue.component("Message", Message);

// init router and vuex
const router = new Router({
    routes
});
const store = new Vuex.Store(stores);
Vue.config.debug = true;

Vue.prototype.$Message = Message;
window.$Message = Message;

// init vue
new Vue({
    el: "#app",

import Vue from "vue";
import App from "./app";
import Vuex from "vuex";
import { stores } from "../../store/pages/chat";
import VueAxios from "vue-axios";
import axios from "assets/axios";
import "root/node_modules/iview/dist/styles/iview.css";

// vuex
Vue.use(Vuex);
Vue.use(VueAxios, axios);

// 按需引入iview组件
import { Button, Form, Input, Icon, Message } from "iview";
Vue.component("Form", Form);
Vue.component("FormItem", Form.Item);
Vue.component("Input", Input);
Vue.component("Button", Button);
Vue.component("Icon", Icon);
Vue.prototype.$Message = Message;
window.$Message = Message;

// init vuex
const store = new Vuex.Store(stores);
Vue.config.debug = true;

// init vue
new Vue({
    el: "#app",
    template: "",
    components: { App },
    store

// 按需引入iview组件
import { Table, Timeline, Menu, Icon, Progress, Cascader,
    Button, Form, Input, Message, Dropdown, Spin } from "iview";
import { Row, Col } from "iview/src/components/grid";
Vue.component("Table", Table);
Vue.component("MenuItem", Menu.Item);
Vue.component("Menu", Menu);
Vue.component("Row", Row);
Vue.component("Col", Col);
Vue.component("Icon", Icon);
Vue.component("Button", Button);
Vue.component("TimelineItem", Timeline.Item);
Vue.component("Progress", Progress);
Vue.component("Form", Form);
Vue.component("FormItem", Form.Item);
Vue.component("Input", Input);
Vue.component("Dropdown", Dropdown);
Vue.component("DropdownMenu", Dropdown.Menu);
Vue.component("DropdownItem", Dropdown.Item);
Vue.component("Cascader", Cascader);
Vue.component("Spin", Spin);
Vue.prototype.$Message = Message;
window.$Message = Message;  // eslint-disable-line

// init vuex
const router = new Router({
    routes
});
const store = new Vuex.Store(stores);
Vue.config.debug = true;