Can't reload background image when dismissing - ios

Question

I need to reload a background image in the MainVC when the user chooses it from the ViewController that will be dismissed but I can't figure out how. Any idea?
Ps. In the MainVC I have a collectionView, every cell contain another collectionView and these collectionViews have a custom cell.
When the user chooses a background image that image is passed to the custom cell and should be set as background.
Protocol
protocol ThemeDelegate {
func handlePassThemeData(data: UIImage)
}
MainVC
class MainVC: UIViewController, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource, ThemeDelegate {
var currentTheme = UIImage(named: "4")!
let collectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .vertical
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
collectionView.translatesAutoresizingMaskIntoConstraints = false
collectionView.register(QuoteCell.self, forCellWithReuseIdentifier: reuseIdentifier)
collectionView.register(FeaturedCell.self, forCellWithReuseIdentifier: featuredReuseIdentifier)
collectionView.register(AuthorCell.self, forCellWithReuseIdentifier: authorReuseIdentifier)
return collectionView
}()
override func viewDidLoad() {
super.viewDidLoad
setUpViews()
setupNavigationBarItems()
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if indexPath.item == 0 {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath) as! QuoteCell
createGradientLayer(bounds: CGRect(x: 0, y: 0, width: cell.frame.width, height: cell.frame.height), cell: cell)
cell.delegate = self
cell.imageToPass = currentTheme
return cell
} else if indexPath.item == 1 {
...
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
if indexPath.item == 0 {
return CGSize(width: view.frame.width, height: view.frame.height / 1.5)
} else if indexPath.item == 1 {
return CGSize(width: view.frame.width, height: view.frame.height / 1.95)
} else {
return CGSize(width: view.frame.width, height: 160)
}
}
func setupNavigationBarItems() {
let themesButton = setUpBarButton(image: #imageLiteral(resourceName: "themes_icon_color"))
themesButton.addTarget(self, action: #selector(handleThemesTapped), for: .touchUpInside)
navigationItem.leftBarButtonItem = UIBarButtonItem(customView: themesButton)
}
func setUpViews() {
view.addSubview(collectionView)
collectionView.delegate = self
collectionView.dataSource = self
collectionView.anchors(top: view.safeAreaLayoutGuide.topAnchor, left: view.leftAnchor, bottom: view.bottomAnchor, right: view.rightAnchor)
}
func handlePassThemeData(data: UIImage) {
self.currentTheme = data
self.collectionView.reloadData()
}
#objc func handleThemesTapped() {
let themesVc = ThemesVC(collectionViewLayout: UICollectionViewFlowLayout())
let navController = UINavigationController(rootViewController: themesVc)
themesVc.delegate = self
navigationController?.present(navController, animated: true, completion: nil)
}
}
MainVC Cell with ColletionView
class QuoteCell: UICollectionViewCell, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource {
var imageToPass = UIImage(named: "2")!
let collectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
collectionView.translatesAutoresizingMaskIntoConstraints = false
collectionView.register(QuoteSubCell.self, forCellWithReuseIdentifier: "cell")
return collectionView
}()
override init(frame: CGRect) {
super.init(frame: frame)
setUpViews()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! QuoteSubCell
cell.quote = quotes[indexPath.item]
cell.setupCell(with: imageToPass)
return cell
}
func setUpViews() {
addSubview(collectionView)
collectionView.delegate = self
collectionView.dataSource = self
collectionView.anchors(top: nameLabel.bottomAnchor, left: leftAnchor, bottom: bottomAnchor, right: rightAnchor)
}
}
CustomCell
class QuoteSubCell: UICollectionViewCell {
var backgroundImage: UIImageView = {
let view = UIImageView()
view.clipsToBounds = true
view.contentMode = .scaleAspectFill
view.image = UIImage(named: "2")
return view
}()
override init(frame: CGRect) {
super.init(frame: frame)
setUpViews()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func setupCell(with image: UIImage) {
backgroundImage.image = image
}
func setUpViews() {
contentView.addSubview(backgroundImage)
backgroundImage.anchors(top: contentView.topAnchor, left: contentView.leftAnchor, bottom: contentView.bottomAnchor, right: contentView.rightAnchor)
}
}
ThemesVC where the user chooses the background
class ThemesVC: UICollectionViewController, UICollectionViewDelegateFlowLayout {
var delegate: ThemeDelegate?
override func viewDidLoad() {
super.viewDidLoad()
collectionView.dataSource = self
collectionView.delegate = self
setUpViews()
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath) as! ThemeCell
cell.backgroundImage.image = themeCell.backgroundImages[indexPath.item]
cell.layer.cornerRadius = 10
return cell
}
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
delegate?.handlePassThemeData(data: themeCell.backgroundImages[indexPath.item])
self.navigationController?.dismiss(animated: true, completion: nil)
}
func setUpViews() {
collectionView.register(ThemeCell.self, forCellWithReuseIdentifier: reuseIdentifier)
collectionView.backgroundColor = UIColor(white: whitePoint, alpha: 1)
collectionView.alwaysBounceVertical = true
collectionView.showsVerticalScrollIndicator = false
}
}

Answer 1

You almost got it right.
class MainVC: UIViewController, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource, ThemeDelegate {
//MARK: Properties
var currentTheme = UIImage(named: "defaultImage")
override func viewDidLoad() {
super.viewDidLoad()
setUpViews()
}
func setUpViews() {
view.addSubview(collectionView)
collectionView.anchors(top: view.safeAreaLayoutGuide.topAnchor, left: view.leftAnchor, bottom: view.bottomAnchor, right: view.rightAnchor)
}
func handlePassThemeData(data: UIImage) {
self.currentTheme = data //override your variable with the new image
self.collectionView.reloadData() //reload the collectionView, to apply the change
}
#objc func handleThemesTapped() {
let themesVc = ThemesVC(collectionViewLayout: UICollectionViewFlowLayout())
themesVc.delegate = self
//no need to instantiate a new navigationController. Just push to the current one, if you want the animation from right, and not from bottom-up.
navigationController?.pushViewController(themesVc, animated: true)
}
}
Delegates should always be weak referenced.
class ThemesVC: UICollectionViewController, UICollectionViewDelegateFlowLayout {
weak var delegate: ThemeDelegate?
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
delegate?.handlePassThemeData(data: themeCell.backgroundImages[indexPath.item])
self.navigationController?.popViewController(animated: true)
}
}
Also, you don't need to create a static variable inside the cell. Instead, pass your currentImage to your cell's variable imageToPass in the method cellForItemAt.
class QuoteCell: UICollectionViewCell, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource {
var imageToPass = UIImage(named: "defaultImage")//pass this image to the cells inside the collectionView
override init(frame: CGRect) {
super.init(frame: frame)
setUpViews()
}
func setUpViews() {
addSubview(collectionView)
collectionView.anchors(top: nameLabel.bottomAnchor, left: leftAnchor, bottom: bottomAnchor, right: rightAnchor)
}
}
Finally, your subCells should show your image:
class QuoteSubCell: UICollectionViewCell {
var backgroundImage: UIImageView = {
let view = UIImageView()
view.clipsToBounds = true
view.contentMode = .scaleAspectFill
view.image = QuoteSubCell.chosenTheme
return view
}()
override init(frame: CGRect) {
super.init(frame: frame)
setUpViews()
}
private func setUpViews() {
contentView.addSubview(backgroundImage)
backgroundImage.anchors(top: contentView.topAnchor, left: contentView.leftAnchor, bottom: contentView.bottomAnchor, right: contentView.rightAnchor)
}
func setupCell(with image: UIImage) { //use this setup function inside "cellForItemAt" method, where you will pass the `imageToPass` image.
backgroundImage.image = image
}
}
UPDATE:
cellForItemAt inside MainVC:
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if indexPath.item == 0 {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath) as! QuoteCell
createGradientLayer(bounds: CGRect(x: 0, y: 0, width: cell.frame.width, height: cell.frame.height), cell: cell)
cell.delegate = self
cell.imageToPass = currentTheme //here you pass the image the 1st time
return cell
} else if indexPath.item == 1 {
...
}
}
cellForItemAt inside QuoteCell:
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! QuoteSubCell
cell.quote = quotes[indexPath.item]
cell.setupCell(with: imageToPass) //here you pass the image the second time
return cell
}
If you're still unable to make it work, I will ask you to share the code from the cellForItemAt methods from the both collectionViews.