创建图层只是保存lyr，此路不通

Provides access to members that control the reading and writing of layer document files.

使用的是    ILayerFile  接口。

// create a new LayerFile instance
        ILayerFile layerFile = new LayerFileClass();
        //create a new layer file
        layerFile.New(saveFileDialog.FileName);
        //attach the layer file with the actual layer
        layerFile.ReplaceContents((ILayer)customProperty);
       // savee the layer file
        layerFile.Save();