'UICollectionView error: cells must be retrieved by calling -: -dequeueReusableCellWithReuseIdentifier:forIndexPath:
In my project I have multiple types of UITableview cell each containing UICollectionview.
Initially I loaded 2 tableViewcell in 2 sections of UITableview. At first it loads fine without any problem. If I scroll the first section it scrolls nice but when I try to scroll the second section it gives me the following error:
the cell returned from -collectionView:cellForItemAtIndexPath: does not have a reuseIdentifier - cells must be retrieved by calling -dequeueReusableCellWithReuseIdentifier:forIndexPath:
I have the following code to set up the process:
class Home: UITableViewDelegate, UITableViewDataSource, UICollectionViewDelegate, UICollectionViewDataSource{
override func viewDidLoad() {
self.tableView.register(SliderViewCell.nib, forCellReuseIdentifier: SliderViewCell.identifier)
self.tableView.register(GridViewCell.nib, forCellReuseIdentifier: GridViewCell.identifier)
self.tableView.estimatedRowHeight = 80
self.tableView.rowHeight = UITableViewAutomaticDimension
}
func numberOfSections(in tableView: UITableView) -> Int {
return 2
}
func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
let viewObj = self.viewObject[indexPath.section]
if viewObj.itemType! == HomeViewItemType.Slider.rawValue{
if let sliderCell = cell as? SliderViewCell {
sliderCell.setCollectionViewDataSourceDelegate(self, forRow: indexPath.row)
}
}
else if viewObj.itemType! == HomeViewItemType.Grid.rawValue{
if let gridCell = cell as? GridViewCell {
gridCell.setCollectionViewDataSourceDelegate(self, forRow: indexPath.row)
}
}
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if self.viewObject.count>0{
let viewObj = self.viewObject[indexPath.section]
if viewObj.itemType! == HomeViewItemType.Slider.rawValue{
let cell:SliderViewCell = tableView.dequeueReusableCell(withIdentifier: SliderViewCell.identifier, for: indexPath) as! SliderViewCell
cell.contentView.tag = indexPath.section
return cell
}
else if viewObj.itemType! == HomeViewItemType.Grid.rawValue{
let cell:GridViewCell = tableView.dequeueReusableCell(withIdentifier: GridViewCell.identifier, for: indexPath) as! GridViewCell
cell.contentView.tag = indexPath.section
return cell
}
}
return UITableViewCell()
}
func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
print("selected")
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return self.viewObject[section].viewData.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if viewObj.itemType! == HomeViewItemType.Slider.rawValue{
if let cell:SliderCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: SliderCollectionViewCell.identifier, for: indexPath) as? SliderCollectionViewCell{
if viewObj.viewData.count>0{
if let imageURL = URL(string: viewData.imageLink!){
cell.icon.sd_setImage(with: imageURL, completed: nil)
}
}
return cell
}
}
else if viewObj.itemType! == HomeViewItemType.Grid.rawValue{
if let cell:GridCollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: GridCollectionViewCell.identifier, for: indexPath) as? GridCollectionViewCell{
if viewObj.viewData.count>0{
if let imageURL = URL(string: viewData.icon!){
cell.icon.sd_setImage(with: imageURL, completed: nil)
}
}
return cell
}
}
return UICollectionViewCell()
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
print("tapped")
}
}
class SliderViewCell: UITableViewCell {
@IBOutlet weak var collectionView: UICollectionView!
static var nib:UINib {
return UINib(nibName: identifier, bundle: nil)
}
static var identifier:String {
return String(describing: SliderViewCell.self)
}
var collectionViewCellWidth : CGFloat = 15.0
var collectionViewCellHeight : CGFloat = 150.0
var cellSpaceWidth : CGFloat = 8.0
override func awakeFromNib() {
super.awakeFromNib()
self.configureCollectionViewCell(nibFile: SliderCollectionViewCell.nib, identifier: SliderCollectionViewCell.identifier, width: collectionView.frame.size.width, height: 80, topInset: 0, leftInset: 0, bottomInset: 0, rightInset: 0, cellSpace: cellSpaceWidth, interimSpace: 0.0, scrollInDirection: .horizontal)
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
}
class GridViewCell: UITableViewCell {
@IBOutlet weak var collectionView: UICollectionView!
static var nib:UINib {
return UINib(nibName: identifier, bundle: nil)
}
static var identifier:String {
return String(describing: GridViewCell.self)
}
var collectionViewCellWidth : CGFloat = 15.0
var collectionViewCellHeight : CGFloat = 150.0
var cellSpaceWidth : CGFloat = 8.0
override func awakeFromNib() {
super.awakeFromNib()
self.configureCollectionViewCell(nibFile: GridCollectionViewCell.nib, identifier: GridCollectionViewCell.identifier, width: collectionView.frame.size.width, height: 80, topInset: 0, leftInset: 0, bottomInset: 0, rightInset: 0, cellSpace: cellSpaceWidth, interimSpace: 0.0, scrollInDirection: .horizontal)
}
func configureCollectionViewCell(nibFile:UINib, identifier:String,width:CGFloat,height:CGFloat, topInset:CGFloat,leftInset:CGFloat,bottomInset:CGFloat,rightInset:CGFloat, cellSpace:CGFloat, interimSpace:CGFloat,scrollInDirection:UICollectionViewScrollDirection){
let nib = nibFile
collectionView.register(nib, forCellWithReuseIdentifier: identifier)
let cellWidth : CGFloat = width//collectionView.frame.size.width
let cellheight : CGFloat = height//collectionViewCellHeight
let cellSize = CGSize(width: cellWidth , height:cellheight)
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = scrollInDirection
layout.itemSize = cellSize
layout.sectionInset = UIEdgeInsets(top: topInset, left: leftInset, bottom: bottomInset, right: rightInset)
layout.minimumLineSpacing = cellSpace
layout.minimumInteritemSpacing = interimSpace
collectionView.setCollectionViewLayout(layout, animated: true)
collectionView.reloadData()
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
}
extension GridViewCell{
func setCollectionViewDataSourceDelegate<D: UICollectionViewDataSource & UICollectionViewDelegate>(_ dataSourceDelegate: D, forRow row:Int){
collectionView.delegate = dataSourceDelegate
collectionView.dataSource = dataSourceDelegate
collectionView.reloadData()
}
}
I think the GridViewCell which loads in the 2nd section of UITableview causing the problem. But I've already added dequeueReusableCellWithReuseIdentifier in the collectionView:cellForItemAtIndexPath: method. So I'm clueless what's causing the error.
Any help would be greatly appreciated.
Solution 1:[1]
The problem may be caused because you are returning UICollectionViewCell() in
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell
if the two conditions are not met.
If at any point the conditions are not met, you return a cell which is not retrieved by calling dequeueReusableCellWithReuseIdentifier:forIndexPath: as the exception says.
Try setting a breakpoint to confirm if this is what is actually happening.
Solution 2:[2]
Here are two ways that you can use to handle your cells instead of if else then UICollectionViewCell()
let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath)
if let gridCell = cell as? GridCollectionViewCell {
// TODO: configure cell
}
return cell
Another way is to
guard let cell = collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, forIndexPath: indexPath)
as? GridCollectionViewCell else {
//Handle error first so you can return a perfect cell if there is no error
}
Remove UICollectionViewCell() it's causing the issue because there is no reuse identifier for that cell.
Solution 3:[3]
i resolve this problem by i missed to return cell in one collection view. i am using multiple collection view and i missed to return cell in " let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CropName", for: indexPath) as! CropNameCollectionViewCell return cell
see somewhere you missed to return cell
Solution 4:[4]
this happened to me too, with the following code:
func collectionView(_ collectionView: UICollectionView, cellForItemAt
indexPath: IndexPath) -> UICollectionViewCell {
guard let cell =
collectionView.dequeueReusableCell(withReuseIdentifier:
"selectedUserCell", for: indexPath) as? selectedUserCell else { return
UICollectionViewCell() }
return cell
}
The problem was that I forgot to assign the class selectedUserCell to the cell in storyboard/nib.. so once that was fixed, the correct cell was being returned.
Solution 5:[5]
Select collection view cell and add reuse identifier
Solution 6:[6]
I doubt the error come from this line return UICollectionViewCell(), could you use assert to check error condition ?
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
// ....
// I doubt error come from `return UICollectionViewCell()`
// Could you insert `assert` to check error condition ?
// assert(false,'Error condition for collectionView cell')
return UICollectionViewCell()
}
Solution 7:[7]
Had this issue today. Truly the phrase "return cell" where cell is a UICollectionViewCell causes this issue.
My issue was because I was using guard let to unwrap an optional, and due to the fact that the function returns something, which in this case is a UICollectionViewCell, it expects that I return one. So I returned a UICollectionViewCell to shut out the error. Definitely, it came back to hunt me.
guard let model = titles[indexPath.row].posterPath else {
print("something went wrong")
return TitleCollectionViewCell()}
So i was able to resolve by using nil coalescing which would not require that I return anything like in guard let method.
let model = titles[indexPath.row].posterPath ?? ""
return cell
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | John Snow |
| Solution 2 | Moaz Khan |
| Solution 3 | keshav |
| Solution 4 | Akram Husseini |
| Solution 5 | Mahendra |
| Solution 6 | AechoLiu |
| Solution 7 | Tesleem |