[_NSConcreteObservation center]: нераспознанный селектор отправлен в класс 'Получение случайных ошибок, подобных этой, при обновлении моего collectionView?

Question

На самом деле я создаю менеджер загрузок для разных категорий. И я застрял здесь. Я получаю эти ошибки в этой строке

self.videoListCollectionView.setCollectionViewLayout (flowLayout, animated: false)

func layoutCollectionView () {

  if categoryFilter == "video" {
        self.getData()

        self.videoListCollectionView.collectionViewLayout.invalidateLayout()
        self.videoListCollectionView.register(UINib.init(nibName: "MessageItemCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: "Cell_Identifier")
        let flowLayout = UICollectionViewFlowLayout.init()
        flowLayout.scrollDirection = .vertical
        flowLayout.itemSize = CGSize(width: UIScreen.main.bounds.size.width-10, height: 220)
        flowLayout.minimumLineSpacing = 10
        self.videoListCollectionView.setCollectionViewLayout(flowLayout, animated: false)
        //self.videoListCollectionView.collectionViewLayout = flowLayout
        self.videoListCollectionView.dataSource = self
        self.videoListCollectionView.delegate = self
        self.videoListCollectionView.reloadData()


    }else if categoryFilter == "audio"{
            self.getData()

        self.videoListCollectionView.collectionViewLayout.invalidateLayout()
        self.videoListCollectionView.register(UINib.init(nibName: "DownloadCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: "Cell_Identifier1")
        let flowLayout1 = UICollectionViewFlowLayout.init()
        flowLayout1.scrollDirection = .vertical
        flowLayout1.itemSize = CGSize(width: UIScreen.main.bounds.size.width-10, height: 80)
        flowLayout1.minimumLineSpacing = 10
        self.videoListCollectionView.setCollectionViewLayout(flowLayout1, animated: false)
        //self.videoListCollectionView.collectionViewLayout = flowLayout1
        self.videoListCollectionView.dataSource = self
        self.videoListCollectionView.delegate = self
        self.videoListCollectionView.reloadData()

}else if categoryFilter == "notes"{
        //self.getData()
        self.videoListCollectionView.collectionViewLayout.invalidateLayout()
        self.videoListCollectionView.register(UINib.init(nibName: "DownloadNoteCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: "Cell_Identifier2")
        let flowLayout2 = UICollectionViewFlowLayout.init()
        flowLayout2.scrollDirection = .vertical
        flowLayout2.itemSize = CGSize(width: UIScreen.main.bounds.size.width-10, height: 80)
        flowLayout2.minimumLineSpacing = 10
        self.videoListCollectionView.setCollectionViewLayout(flowLayout2, animated: false)
        //self.videoListCollectionView.collectionViewLayout = flowLayout1
        self.videoListCollectionView.dataSource = self
        self.videoListCollectionView.delegate = self
        self.videoListCollectionView.reloadData()


}

2018-01-09 17: 26: 44.024 LCM-iOSApp [16990: 626500] + [_ NSConcreteObservation center]: нераспознанный селектор отправлен в класс 0x10b66b038 2018-01-09 17:26:44.048 LCM-iOSApp[16990:626500]

Завершение работы приложения из-за невыполненной исключительной ситуации NSInvalidArgumentException, причина: '+[_NSConcreteObservation center]: нераспознанный селектор, отправленный в класс 0x10b66b038' *** Стек первого вызова вызова:

0   CoreFoundation                      0x000000010c1b8b0b exceptionPreprocess + 171
1   libobjc.A.dylib                     0x000000010b808141 objc_exception_throw + 48
2   CoreFoundation                      0x000000010c228074 +[NSObject(NSObject) doesNotRecognizeSelector:] + 132
3   CoreFoundation                      0x000000010c13f840 ___forwarding___ + 1024
4   CoreFoundation                      0x000000010c13f3b8 _CF_forwarding_prep_0 + 120
5   UIKit                               0x000000010e45b3c4 -[UICollectionView _setCollectionViewLayout:animated:isInteractive:completion:animator:] + 1732
6   UIKit                               0x000000010e45ace9 -[UICollectionView _setCollectionViewLayout:animated:isInteractive:completion:] + 76
7   UIKit                               0x000000010e45aa46 -[UICollectionView setCollectionViewLayout:animated:] + 429
8   LCM-iOSApp                          0x0000000109ced2a8 _TFC10LCM_iOSApp23DownloadsViewController20layoutCollectionViewfT_T_ + 5336
9   LCM-iOSApp                          0x0000000109ce1e1d _TFFC10LCM_iOSApp23DownloadsViewController21MessagesListingFilterFP_T_U1_FT_T_ + 1693
10  LCM-iOSApp                          0x0000000109968d17 _TTRXFo___XFdCb___ + 39
11  libdispatch.dylib                   0x000000010fe094a6 _dispatch_call_block_and_release + 12
12  libdispatch.dylib                   0x000000010fe3205c _dispatch_client_callout + 8
13  libdispatch.dylib                   0x000000010fe1340b _dispatch_main_queue_callback_4CF + 411
14  CoreFoundation                      0x000000010c17d909 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 9
15  CoreFoundation                      0x000000010c143ae4 __CFRunLoopRun + 2164
16  CoreFoundation                      0x000000010c143016 CFRunLoopRunSpecific + 406
17  GraphicsServices                    0x00000001141c9a24 GSEventRunModal + 62
18  UIKit                               0x000000010db1d134 UIApplicationMain + 159
19  LCM-iOSApp                          0x0000000109c78f87 main + 55
20  libdyld.dylib                       0x000000010fe7e65d start

libC++abi.dylib: завершается с необработанным исключением типа NSException (lldb)