在游戏入口实例化玩一个加载TiledMap地图的类(loadMap)后，想通过该对象获取到被加载地图的一个MapLayer层。也就是说，加载TiledMap和获取该地图的MapLayer（某一层）都放到一个类里面，只要通过实例化的对象就能直接调用MapLayer.具体怎么实现呢。获取地图层一定要在_proto.mapLoaaded里面吗？

/*
* name;
*/
var TiledMap = Laya.TiledMap;
var Rectangle = Laya.Rectangle;
var Handler = Laya.Handler;
var Sprite = Laya.Sprite;
var MapLayer = Laya.MapLayer;
var loadMap = (function (_super) {
    function loadMap() {
        loadMap.super(this);
    }
    Laya.class(loadMap,"loadMap",_super);
    var _proto = loadMap.prototype;
    _proto.init = function() {
        this.num = "";
        this.map = new TiledMap();
    }
    _proto.showMap = function(num) {
        this.num = num;
        this.map.createMap("map/level/mota_map" + num + ".json",new Rectangle(0,0,448,448),Handler.create(this,this.mapLoaded));}
     
    _proto.mapLoaded = function(){
        this.pass = this.map.getLayerByIndex(0);//获取通行层
        console.log(this.pass);
    }
    _proto.getLayer = function() {
        this.floor = this.map.getLayerByIndex(0);//获取通行层
        console.log(this.pass);
    }
    console.log(this.map)
    return loadMap;

})(Sprite);

**游戏主入口**

var Main = (function (){
    (function Main(){
        Laya.init(448,448);
        var map1 = new loadMap();
        map1.init();
        map1.showMap("3");
        map1.getLayer();
        console.log(map1.num);
        console.log(map1);
        console.log(map1.pass);
        console.log(map1.getLayer);
    })();
    return Main;

})();