Collectionview not showing - ios

Question

I am trying to achieve a feature that whenever I tap a button from the collectionview at the bottom, the specific value that was tapped will reflect on the collectionview in the middle. So far, I have achieved the bottom collectionview, but I am not sure what is wrong with my code that my new collectionview isn't showing.
import UIKit
class MyButtonCell: UICollectionViewCell{
#IBOutlet weak var buttonOne: UIButton!
#IBOutlet weak var targetButton: UIButton!
var callback: (() -> ())?
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
commonInit()
}
func commonInit() -> Void {
contentView.layer.borderWidth = 1
contentView.layer.borderColor = UIColor.black.cgColor
}
#IBAction func buttonTapped(_ sender: UIButton) {
callback?()
}
}
class StevenViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource,UICollectionViewDelegateFlowLayout {
let buttonTitles: [String] = [
"4", "6", "7", "8"
]
var targetButtonTitles: [String] = []
//number array
#IBOutlet var collectionView: UICollectionView!
#IBOutlet weak var targetCollection: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
collectionView.delegate = self
collectionView.dataSource = self
targetCollection.delegate = self
targetCollection.dataSource = self
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return buttonTitles.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "myCellID", for: indexPath) as! MyButtonCell
let targetCell = targetCollection.dequeueReusableCell(withReuseIdentifier: "target", for: indexPath) as! MyButtonCell
// set the button title (and any other properties)
cell.buttonOne.setTitle(buttonTitles[indexPath.item], for: [])
// set the cell's callback closure
cell.callback = {
print("Button was tapped at \(indexPath)")
self.targetButtonTitles.append(self.buttonTitles[indexPath.item])
print(self.targetButtonTitles)
targetCell.targetButton.setTitle(self.targetButtonTitles[indexPath.item], for: [])
// do what you want when the button is tapped
}
return cell
}
}
My storyboard:
What's showing in the simulator:

Answer 1

Try this out.
In your cellForItemAtIndexPath you must return both cells in order to show them both.
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "myCellID", for: indexPath) as! MyButtonCell
let targetCell = targetCollection.dequeueReusableCell(withReuseIdentifier: "target", for: indexPath) as! MyButtonCell
if collectionView == self.collectionView {
// Setup here your cell
cell.callback = {
print("Button was tapped at \(indexPath)")
self.targetButtonTitles.append(self.buttonTitles[indexPath.item])
print(self.targetButtonTitles)
targetCell.targetButton.setTitle(self.targetButtonTitles[indexPath.item], for: [])
// do what you want when the button is tapped
}
cell.buttonOne.setTitle(buttonTitles[indexPath.item], for: [])
return cell
} else {
// Setup here your targetCell
return targetCell
}
Note that also if you have a different number of sections for each collectionView, you must return them independently.
func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if collectionView == self.collectionView {
return 1 // Number of sections of your collectionView
}
return 1 // Number of sections of your targetCollection
}