ImageView of a custom CollectionViewCell is nil when it should be configured - ios

Question

I have a tableViewCell with a collectionView, collectionView's cells are custom ones, they contains just a imageView.
Here is my test project
Here are DataSource required methods from my CollectionView class:
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ImageCell", for: indexPath) as! ImageCell
let image = UIImage(named: listItems[indexPath.row])
cell.testImageView.image = image
return cell
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return listItems.count
}
When I try to set image for cell's imageView I get this error:
fatal error: unexpectedly found nil while unwrapping an Optional value
I have checked image, it isn't nil, but testImageView is, I get this error when I try to set image to collectionViewCell's testImageView.
How can I fix it?
EDIT1
Here is method called from tableViewController to fill collectionView's listItem
func load(listItem: [String]) {
self.listItems = listItem
reloadData()
}
Also if I remove code from collectionView cellForItemAt indexPath with this one all is working fine
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ImageCell", for: indexPath)
let imageView = UIImageView(image:UIImage(named: listItems[indexPath.row]))
cell.backgroundView = imageView

Answer 1

You have mistaken your two view controllers. Your IB outlet is connected to a cell in a different view controller. I mean you can have multiple views in different controllers connected to a same IBOutlet, but in your case the one that loads first is not connected, so that is why it crashes.
This is the cell your outlet was connected to.
This is that you are trying to load (but did not connect IBOutlet to image view):

Answer 2

Just in case you want to use code instead..
import UIKit
class ImageCell : UICollectionViewCell {
private var imageView: UIImageView!
private var descLabel: UILabel!
public var image: UIImage? {
get {
return self.imageView.image
}
set {
self.imageView.image = newValue
}
}
public var imageDesc: String? {
get {
return self.descLabel.text
}
set {
self.descLabel.text = newValue
}
}
override init(frame: CGRect) {
super.init(frame: frame)
self.initControls()
self.setTheme()
self.doLayout()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
self.initControls()
self.setTheme()
self.doLayout()
}
override func awakeFromNib() {
super.awakeFromNib()
}
func initControls() {
self.imageView = UIImageView()
self.descLabel = UILabel()
}
func setTheme() {
self.imageView.contentMode = .scaleAspectFit
self.descLabel.numberOfLines = 1
self.descLabel.lineBreakMode = .byWordWrapping
self.descLabel.textAlignment = .center
self.descLabel.textColor = UIColor.black
self.contentView.backgroundColor = UIColor.white
}
func doLayout() {
self.contentView.addSubview(self.imageView)
self.contentView.addSubview(self.descLabel)
self.imageView.leftAnchor.constraint(equalTo: self.contentView.leftAnchor, constant: 5).isActive = true
self.imageView.rightAnchor.constraint(equalTo: self.contentView.rightAnchor, constant: -5).isActive = true
self.imageView.topAnchor.constraint(equalTo: self.contentView.topAnchor, constant: 0).isActive = true
self.descLabel.leftAnchor.constraint(equalTo: self.contentView.leftAnchor, constant: 5).isActive = true
self.descLabel.rightAnchor.constraint(equalTo: self.contentView.rightAnchor, constant: -5).isActive = true
self.descLabel.topAnchor.constraint(equalTo: self.imageView.bottomAnchor, constant: 5).isActive = true
self.descLabel.bottomAnchor.constraint(equalTo: self.contentView.bottomAnchor, constant: -5).isActive = true
for view in self.contentView.subviews {
view.translatesAutoresizingMaskIntoConstraints = false
}
}
}
class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
private var collectionView: UICollectionView!
private var dataSource: Array<String>!
override func viewDidLoad() {
super.viewDidLoad()
self.initDataSource()
self.initControls()
self.setTheme()
self.registerClasses()
self.doLayout()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
func initDataSource() {
self.dataSource = ["Image1", "Image2", "Image3", "Image4", "Image5", "Image6"]
}
func initControls() {
let layout = UICollectionViewFlowLayout()
layout.itemSize = CGSize(width: 117, height: 125)
layout.invalidateLayout()
self.collectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)
self.collectionView.delegate = self
self.collectionView.dataSource = self
}
func setTheme() {
self.collectionView.backgroundColor = UIColor.clear
self.edgesForExtendedLayout = UIRectEdge(rawValue: 0)
self.view.backgroundColor = UIColor.blue
}
func registerClasses() {
self.collectionView.register(ImageCell.self, forCellWithReuseIdentifier: "ImageCellIdentifier")
}
func doLayout() {
self.view.addSubview(self.collectionView)
self.collectionView.leftAnchor.constraint(equalTo: self.view.leftAnchor).isActive = true
self.collectionView.rightAnchor.constraint(equalTo: self.view.rightAnchor).isActive = true
self.collectionView.topAnchor.constraint(equalTo: self.view.topAnchor).isActive = true
self.collectionView.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
for view in self.view.subviews {
view.translatesAutoresizingMaskIntoConstraints = false
}
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return self.dataSource.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ImageCellIdentifier", for: indexPath) as! ImageCell
let imageName = self.dataSource[indexPath.row]
cell.image = UIImage(named: imageName)
cell.imageDesc = imageName
return cell
}
}
http://imgur.com/o7O7Plw

Answer 3

maybe the "testImageView" outlet variable is not connected from the interface builder or there is no CollectionViewCell with reuseIdentifier "ImageCell". Check whether cell is nil or not using LLDB po command.