Sencha removed the refreshFn from the pullrefresh plugin in ST 2.2. Here is an user extension with gives the old
functionality back to you.

/**

 * This user extension gives st 2.3.0 Pullrefresh the RefreshFn back

 * based on sencha touch 2.3.0

 *

 * @class Ext.ux.touch.PullRefreshFn

 * @version 2.0.1-beta

 * @author Martin Hess <https://github.com/p5hema2>

 *

 * ## Example

 *

 *     Ext.create('Ext.dataview.List', {

 *         fullscreen: true,

 *

 *         store: store,

 *

 *         plugins: [

 *             {

 *                 xclass: 'Ext.ux.touch.PullRefreshFn',

 *                 pullRefreshText: 'Pull down for more new Tweets!'

 *                 refreshFn: function() {

 *                        Ext.getStore('ENTER YOUR STORE HERE').load('',1)

 *                   }

 *             }

 *         ],

 *

 *         itemTpl: [

 *             'YOUR ITEMTPL'

 *         ]

 *     });

 */

Ext.define('myapp.model.PullRefreshFn', {

    extend: 'Ext.plugin.PullRefresh',

    alias: 'plugin.pullrefreshfn',

    requires: ['Ext.DateExtras'],

    xtype:'refreshFn',

    config: {

        /**

         * @cfg {Function} refreshFn The function that will be called to refresh the list.

         * If this is not defined, the store's load function will be called.

         * The refresh function gets called with a reference to this plugin instance.

         * @accessor

         */

        refreshFn: null,

        pullText: '下拉能够更新',

		  lastUpdatedText:"上次刷新时间",

		  lastUpdatedDateFormat:"Y-m-d H:i",

		  releaseText:"松开開始更新",

		  loadedText:"载入完毕"

    },

    fetchLatest: function() {

        if (this.getRefreshFn()) {

            this.getRefreshFn().call(this, this);

            this.setState("loaded");

            this.fireEvent('latestfetched', this, 'refreshFn, you have to handle toInsert youself');

            if (this.getAutoSnapBack()) {

                this.snapBack();

            }

        } else {

            console.log('fetchLatest')

            var store = this.getList().getStore(),

                proxy = store.getProxy(),

                operation;

            operation = Ext.create('Ext.data.Operation', {

                page: 1,

                start: 0,

                model: store.getModel(),

                limit: store.getPageSize(),

                action: 'read',

                sorters: store.getSorters(),

                filters: store.getRemoteFilter() ? store.getFilters() : []

            });

            proxy.read(operation, this.onLatestFetched, this);

        }

    },

    /**

     * Snaps the List back to the top after a pullrefresh is complete

     * @param {Boolean=} force Force the snapback to occur regardless of state {optional}

     */

    snapBack: function(force) {

        if(this.getState() !== "loaded" && force !== true) return;

        var that = this,

            list = this.getList(),

            scroller = list.getScrollable().getScroller(),

            currentY = scroller.minPosition.y;

        scroller.refresh();

        scroller.minPosition.y = 0;

        scroller.on({

            scrollend: this.onSnapBackEnd,

            single: true,

            scope: this

        });

        this.setIsSnappingBack(true);

        scroller.getTranslatable().translateAnimated(0, currentY, {duration: this.getSnappingAnimationDuration()});

        setTimeout(

            function () {

                scroller.scrollTo(0,1);

                scroller.scrollToTop();

            },

            that.getSnappingAnimationDuration()

        );

    }

});