can't delete item from collectionView - ios

Question

I have simple collectionview which shows 1 column on iphone and 2 columns on iPad
There is a button which removing an item from collectionview but when I press the button I got this error:
The number of sections contained in the collection view after the update (3) must be equal to the number of sections contained in the collection view before the update (4), plus or minus the number of sections inserted or deleted (0 inserted, 0 deleted).'
And this is my code
protocol AudioListDataProtocol: class {
func search(searchText: String)
func playComposition(composition: Composition, data: [Composition], play: Bool)
func endEditing()
}
class AudioListDataAdapter: NSObject, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout, UISearchBarDelegate, AudioItemCellProtocol {
var delegate: AudioListDataProtocol!
var isFavoriesList = false
private var data = [Composition]()
private var collectionView: UICollectionView!
private var searchBar: UISearchBar!
private let cellIdentifier = "AudioCellIdent"
private var selectedIndexPath: IndexPath!
private var cellWidth = 0 as CGFloat
private var sectionCount = 0
private var itemCount = 0
//MARK: public methods
func initSearchBar(searchBar: UISearchBar) -> Void {
self.searchBar = searchBar
self.searchBar.delegate = self
self.searchBar.returnKeyType = .done
self.searchBar.placeholder = DicionaryManager.shared.getStringValue(dKey: AMKeys.mobile_label_search_here)
}
func initCollection(collection: UICollectionView) -> Void {
self.collectionView = collection
self.collectionView.dataSource = self
self.collectionView.delegate = self
self.collectionView.register(UINib.init(nibName: "AudioItemCell", bundle: nil), forCellWithReuseIdentifier: cellIdentifier)
}
func setListData(data: [Composition], itemsPerSection: Int, itemWidth: CGFloat) -> Void {
cellWidth = itemWidth
self.data = data
itemCount = itemsPerSection
sectionCount = Int(ceil(Double(self.data.count / itemCount)))
}
func reload() {
collectionView.reloadData()
}
//MARK: UISearchBarDelegate
func searchBarTextDidBeginEditing(_ searchBar: UISearchBar) {
searchBar.showsCancelButton = true
}
func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
if searchText.characters.count >= 3 {
if let d = delegate {
d.search(searchText: searchText)
}
}
}
func searchBarCancelButtonClicked(_ searchBar: UISearchBar) {
searchBar.text = ""
if let d = delegate {
d.search(searchText: "")
d.endEditing()
}
}
func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {
if let d = delegate {
d.endEditing()
}
}
//MARK: UICollectionViewDataSource
func numberOfSections(in collectionView: UICollectionView) -> Int {
return sectionCount
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return itemCount
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellIdentifier, for: indexPath) as? AudioItemCell {
return cell
}
return UICollectionViewCell()
}
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
let c = cell as! AudioItemCell
c.setupComposition(composition: data[curItemIndex(indexPath: indexPath)])
c.indexPath = indexPath
c.favoriteState = isFavoriesList
c.delegate = self
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
PlayerManager.shared.changePlaylist()
var item: Composition
item = data[curItemIndex(indexPath: indexPath)] as Composition
item.isPlaying = true
item.showPlayer = true
collectionView.reloadItems(at: [indexPath])
selectedIndexPath = indexPath
delegate.playComposition(composition: item, data: data, play: true)
}
func playingCompositionForReload(composition: Composition) {
composition.isPlaying = true
composition.showPlayer = true
collectionView.reloadData()
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: cellWidth, height: 90)
}
//MARK: helpers methods
func updateState(play: Bool) -> Void {
if (selectedIndexPath) != nil {
let item = data[curItemIndex(indexPath: selectedIndexPath)]
item.isPlaying = !item.isPlaying
} else {
selectedIndexPath = IndexPath(row: 0, section: 0)
let item = data[0]
item.isPlaying = true
item.showPlayer = true
}
collectionView.reloadItems(at: [selectedIndexPath])
}
private func curItemIndex(indexPath: IndexPath) -> Int {
return indexPath.section * itemCount + indexPath.item
}
//MARK: AudioItemCellProtocol
func removeCellAtIndexpath(indexPath: IndexPath) {
collectionView.performBatchUpdates({
self.data.remove(at: self.curItemIndex(indexPath: indexPath))
sectionCount = Int(ceil(Double(self.data.count / self.itemCount)))
self.collectionView.deleteItems(at: [indexPath])
}, completion: nil)
}
}
And this button pressed code
delegate.removeCellAtIndexpath(indexPath: indexPath)
What I did wrong here and why its crashing?
Please help I stuck on this a day.

Answer 1

The problem is with your numberOfItemsInSection method and the use of the itemCount property. You are returning a fixed number. You are assuming every section has the same fixed number of items. Instead, you should be returning the current number of records in your data source for the given section.
It would help a lot if you setup your data source to be an array of arrays where the outer array represents your sections and each inner array is the items in that section. Then you simply return the array count instead of some predetermined variable.