Swift - Issue accessing data from UICollectionView embedded in UITableView - ios

Question

I have a tableView, with a prototype cell containing a UICollectionView. I’ve setup the tableView according to this tutorial (https://medium.com/#stasost/ios-how-to-build-a-table-view-with-multiple-cell-types-2df91a206429), and the UI is working. I can pass data through my tableView and into the collectionView.
View Layout
When a collectionViewCell is selected it segues to another view.
I haven’t figured out how to access the data from the collectionViewCell and pass it to the new view.
The collectionView is initialized within the tableView prototype cell. I've tried didSelectRow -> prepareForSegue (code below), but the commands do not autocomplete, and are not working.
Here's the code for the tableViewCell, where the collectionView is setup.
EDIT: Removed commented code for clarity
import UIKit
class homeFeedTableViewCell: UITableViewCell, UICollectionViewDelegate, UICollectionViewDataSource {
#IBOutlet weak var feedCollectionView: UICollectionView!
var selectedEvent : Event?
var collectionItems = [CollectionViewModelItem]()
var collectionItem : CollectionViewModelItem?
#IBOutlet weak var sectionHeadingLabel: UILabel!
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
feedCollectionView.delegate = self
feedCollectionView.dataSource = self
print("collection items \(collectionItems.count)")
for item in collectionItems{print("type: \(item.type), title: \(item.eventTitle)")}
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
// setup view model
var item: TableViewModelItem? {
didSet {
// if not right class, skip
guard let item = item as? TableViewModelFeed else {
return
}
sectionHeadingLabel.text = item.sectionTitle
}
}
// create reuse identifier property
static var identifier: String {
return String(describing: self)
}
}
import Foundation
import UIKit
extension homeFeedTableViewCell {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
// print("dataCount3: \(collectionItems.count) \(collectionItems[collectionItems.count-1].type)")
return collectionItems.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
// let cell = UICollectionViewCell()
// return cell
self.collectionItem = collectionItems[indexPath.row]
switch collectionItem!.type {
case .yourEvents:
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier:YourEventsCollectionViewCell.identifier, for: indexPath) as? YourEventsCollectionViewCell{
cell.item = collectionItem
print(cell.item?.type)
print(".yourEvents")
return cell
}
case .feed:
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: mainFeedCollectionViewCell.identifier, for: indexPath) as? mainFeedCollectionViewCell{
cell.item = collectionItem
print(".feed")
return cell
}
}
return UICollectionViewCell()
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
print("\(collectionItems[indexPath.row].eventTitle) tapped")
func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "yourEventsToEventViewController" || segue.identifier == "feedToEventViewController"{
print("prepare for segue1")
let destinationVC = segue.destination as! EventViewController
if collectionItem != nil{
print("prepare for segue2")
destinationVC.backgroundImageUrl = collectionItem!.backgroundImageUrl
}
}
}
}
}

Answer 1

A UICollectionView keeps track of its selected indexPaths with the property indexPathsForSelectedItems. Since you trigger your segue in collectionView(didSelectItem: atIndexPath:), your selected indexPath is available during prepare(forSegue:). You could try the following:
class MyViewController: UIViewController, UICollectionViewDelegate {
...
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
performSegue(withIdentifier: "mySegue", sender: self)
}
...
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
super.prepare(for: segue, sender: sender)
guard let destinationVC = segue.destination as! EventViewController,
segue.identifier == "mySegue" else { return }
// In this context, your selected cell is the one who fired the segue
if let selectedIndexPaths = collectionView.indexPathsForSelectedItems,
let firstSelectedIndexPath = selectedIndexPaths.first {
let selectedObject = collectionItems[firstSelectedIndexPath.row]
destinationVC?.backgroundUrl = selectedObject.backgroundUrl
}
}
}
The sequence is:
You select a cell (through user interaction, ie tapping).
didSelect performs a segue named "mySegue" (in this example).
In prepareForSegue, you look for your selected index paths. Assuming you aren't using multi-selection, you want your first and only indexPath. Using that index path, you can retrieve your data in your collectionItems array.