I have a view controller that contains a uicollectionview. Each collectionview cell contains a button that, when clicked, adds a new label within the cell. To expand the height of each cell I call reloadItems(at: [indexPath]).
Unfortunately calling reloadItems(at: [indexPath]) fades out the old label and fades in the new label, how do I prevent any labels from fading out?
The bug becomes even more apparent every time I click the addLabel button: a new label fades in but whatever previous labels had not been visible suddenly appear again and whatever labels used to be visible, magically turn invisible again.
reloadItems(at: [indexPath]) seems to toggle the alpha of each new label differently. I would like to resize and add new labels to the cell without having any labels disappear.
Here is my code:
ViewController
class ViewController: UIViewController {
weak var collectionView: UICollectionView!
var expandedCellIdentifier = "ExpandableCell"
var cellWidth:CGFloat{
return collectionView.frame.size.width
}
var expandedHeight : CGFloat = 200
var notExpandedHeight : CGFloat = 50
//the first Int gives the row, the second Int gives the amount of labels in the row
var isExpanded = [Int:Int]()
override func viewDidLoad() {
super.viewDidLoad()
for i in 0..<4 {
isExpanded[i] = 1
}
}
}
extension ViewController:UICollectionViewDataSource{
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return isExpanded.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: expandedCellIdentifier, for: indexPath) as! ExpandableCell
cell.indexPath = indexPath
cell.delegate = self
cell.setupCell = "true"
return cell
}
}
extension ViewController:UICollectionViewDelegateFlowLayout{
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
if isExpanded[indexPath.row]! > 1{
let height = (collectionView.frame.width/10)
let newHeight = height * CGFloat(isExpanded[indexPath.row]!)
return CGSize(width: cellWidth, height: newHeight)
}else{
return CGSize(width: cellWidth, height: collectionView.frame.width/6 )
}
}
}
extension ViewController:ExpandedCellDeleg{
func topButtonTouched(indexPath: IndexPath) {
isExpanded[indexPath.row] = isExpanded[indexPath.row]! + 1
UIView.animate(withDuration: 0.8, delay: 0.0, usingSpringWithDamping: 0.9, initialSpringVelocity: 0.9, options: UIView.AnimationOptions.curveEaseInOut, animations: {
self.collectionView.reloadItems(at: [indexPath])
}, completion: { success in
print("success")
})
}
}
Protocol
protocol ExpandedCellDeleg:NSObjectProtocol{
func topButtonTouched(indexPath:IndexPath)
}
ExpandableCell
class ExpandableCell: UICollectionViewCell {
weak var delegate:ExpandedCellDeleg?
public var amountOfIntervals:Int = 1
public var indexPath:IndexPath!
var setupCell: String? {
didSet {
print("cell should be setup!!")
}
}
let ivAddLabel: UIImageView = {
let imageView = UIImageView()
imageView.translatesAutoresizingMaskIntoConstraints = false
imageView.image = #imageLiteral(resourceName: "plus")
imageView.tintColor = .black
imageView.contentMode = .scaleToFill
imageView.backgroundColor = UIColor.clear
return imageView
}()
override init(frame: CGRect) {
super.init(frame: .zero)
contentView.addSubview(ivAddLabel)
let name = UILabel(frame: CGRect(x: 0, y: 0, width: 100, height: 18))
name.center = CGPoint(x: Int(frame.width)/2 , y: 20)
name.textAlignment = .center
name.font = UIFont.systemFont(ofSize: 16)
name.textColor = UIColor.black
name.text = "Fred"
contentView.addSubview(name)
ivAddLabel.rightAnchor.constraint(equalTo: self.rightAnchor, constant: -14).isActive = true
ivAddLabel.topAnchor.constraint(equalTo: self.topAnchor, constant: 10).isActive = true
ivAddLabel.widthAnchor.constraint(equalToConstant: 20).isActive = true
ivAddLabel.heightAnchor.constraint(equalToConstant: 20).isActive = true
ivAddLabel.layer.masksToBounds = true
ivAddLabel.isUserInteractionEnabled = true
let addGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(ivAddLabelSelected))
ivAddLabel.addGestureRecognizer(addGestureRecognizer)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
@objc func ivAddLabelSelected(){
print("add button was tapped!")
if let delegate = self.delegate{
amountOfIntervals = amountOfIntervals + 1
let height = (20*amountOfIntervals)
let name = UILabel(frame: CGRect(x: 0, y: 0, width: 100, height: 18))
name.center = CGPoint(x: Int(frame.width)/2, y: height)
name.textAlignment = .center
name.font = UIFont.systemFont(ofSize: 16)
name.textColor = UIColor.black
name.text = "newFred"
name.alpha = 0.0
contentView.addSubview(name)
UIView.animate(withDuration: 0.2, animations: { name.alpha = 1.0 })
delegate.topButtonTouched(indexPath: indexPath)
}
}
}
