Unity3d export Xcode..." level0.resS, resource.assets.resS"

Unity3d project exported to Xcode,I find this:

I do not know what the level0.resS,level4.resS,level7.resS is ,resources.assets.resS sharedassets0.asset.res is? The resource.assets.resS is very large,how does it come? I find data in same folder contained in some xxx.ipa load from AppStore only has resource.assets,no level0.resS,level4.resS... Who can tell me why？Expecting for your help ,thanks very much.