swift - iOS App screen freezes when loading more than 2 collection views inside container view -

i have viewcontroller has 4 containers. intent fill containers 4 collectionviews defined on separate viewcontroller. but, problem is, when 4 collection views loaded, cannot app. no buttons nor scrolling happens. freezes- no errors thrown. when load 2 of collection views works fine. idea why happens?

here code:

import uikit  class homeviewcontroller: uiviewcontroller  {       @iboutlet weak var newproductscontainer: uiview!     @iboutlet weak var featuredproductscontainer: uiview!     @iboutlet weak var packagelistcontainer: uiview!     @iboutlet weak var productccontainer: uiview!     @iboutlet weak var discountcontainer: uiview!       override func viewdidload() {         super.viewdidload()         self.createslideshow()         self.setnewproductscontainercontent()         self.setfeaturedcontainercontent()         self.setpackagelistcontainercontent()         print("hello there")     }      func setnewproductscontainercontent(){         let productcollectionvc: productcollectionviewcontroller = storyboard?.instantiateviewcontrollerwithidentifier("productcollection") as! productcollectionviewcontroller         productcollectionvc.collectiontype = "new_products"         self.newproductscontainer.addsubview(productcollectionvc.view)         self.addchildviewcontroller(productcollectionvc)     }      func setfeaturedcontainercontent(){         let productcollectionvc: productcollectionviewcontroller = storyboard?.instantiateviewcontrollerwithidentifier("productcollection") as! productcollectionviewcontroller         productcollectionvc.collectiontype = "new_products"         self.featuredproductscontainer.addsubview(productcollectionvc.view)         self.addchildviewcontroller(productcollectionvc)     }      func setpackagelistcontainercontent(){         let productcollectionvc: productcollectionviewcontroller = storyboard?.instantiateviewcontrollerwithidentifier("productcollection") as! productcollectionviewcontroller         productcollectionvc.collectiontype = "new_products"         self.packagelistcontainer.addsubview(productcollectionvc.view)         self.addchildviewcontroller(productcollectionvc)     }       override func didreceivememorywarning() {         super.didreceivememorywarning()         print("memory warning")     }   } 

hello there printed without problem.

productcollectionviewcontroller

import uikit import kvnprogress import objectmapper import kingfisher  class productcollectionviewcontroller: uiviewcontroller, uicollectionviewdatasource, uicollectionviewdelegate {      @iboutlet weak var productcoll: uicollectionview!      var collectiontype: string = "all_products"     var products: [product] = []      override func viewdidload() {         super.viewdidload()         self.productcoll.datasource = self         self.productcoll.delegate = self         self.initialize()     }      func initialize() {              kvnprogress.show()             serviceprovider.getproductsbylimit(0, limit: 10){ (products: [product]) in                 kvnprogress.dismiss()                 self.products = products                 self.productcoll.reloaddata()             }     }      override func didreceivememorywarning() {         super.didreceivememorywarning()     }      func numberofsectionsincollectionview(collectionview: uicollectionview) -> int {         return 1     }      func collectionview(collectionview: uicollectionview, numberofitemsinsection section: int) -> int {         return products.count     }      func collectionview(collectionview: uicollectionview, cellforitematindexpath indexpath: nsindexpath) -> uicollectionviewcell {         let cell = collectionview.dequeuereusablecellwithreuseidentifier("procell",forindexpath:indexpath) as! procell         let product: product = products[indexpath.row]         cell.title.text = product.title         var prices:[prices] = product.prices         var price = ""         if prices.count > 0 {             price = string(prices[0].retailprice)         }         cell.price.text = price         var pictures: [picture] = product.pictures         print(pictures.count)         if pictures.count > 0 {             cell.image.kf_setimagewithurl(nsurl(string: constants.fineurl+"mallbackoffice/resources/images/product/general/"+pictures[0].name)!)         }         return cell     }      func collectionview(collectionview: uicollectionview, didselectitematindexpath indexpath: nsindexpath) {         print("clicked")     }  } 

getproductsbylimit method uses alamofire fetch data fetched without problem.