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@oliverfoggin
Created January 15, 2022 16:46
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Collection view reload data only reloading items once each...
import UIKit
class MyCollectionViewCell: UICollectionViewCell {
let label: UILabel = UILabel()
override init(frame: CGRect) {
super.init(frame: frame)
contentView.addSubview(label)
label.translatesAutoresizingMaskIntoConstraints = false
label.centerYAnchor.constraint(equalTo: contentView.centerYAnchor).isActive = true
label.centerXAnchor.constraint(equalTo: contentView.centerXAnchor).isActive = true
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
let items: [Int] = Array(1...10)
@IBOutlet weak var collectionView: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
collectionView.register(MyCollectionViewCell.self, forCellWithReuseIdentifier: "cell")
navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .refresh, target: self, action: #selector(reload))
}
@objc func reload() {
print("Reload")
collectionView.reloadData() // logs out "Reload" and then reloads the items, causing each item to log out from the `cellForItemAt` function
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
items.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! MyCollectionViewCell
let item = items[indexPath.item]
print(item) // Logs out 1-10 (items from the array)
cell.label.text = "\(item)"
return cell
}
}
@oliverfoggin
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Here is the collection view...
image

Here is the log. As you can see, each "Reload" then only logs 1...10 once each.
image

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