iOS CollectionView Header doesn't show - ios

Question

Im trying to add a segmented control onto my header but I am having trouble doing this. In this example to make things simpler I am adding a Label but that is also not showing. Can someone tell me why this is not happening?
import UIKit
class SessionsViewController: UICollectionViewController , UICollectionViewDelegateFlowLayout {
override func viewDidLoad() {
super.viewDidLoad()
prepareCollectionView()
view.backgroundColor = UIColor.white
navigationController?.navigationBar.isTranslucent = true
navigationItem.leftBarButtonItem = UIBarButtonItem(title: "Log Out", style: .plain, target: self, action: #selector(handleLogout))
navigationItem.rightBarButtonItem = UIBarButtonItem(image: UIImage(named: "plus") , style: .plain, target: self, action: nil)
navigationItem.rightBarButtonItem?.tintColor = UIColor.honePalette.accent
}
func prepareSegmentedControll()->UISegmentedControl{
let items = ["Future Sessions", "Past Sessions"]
let control = UISegmentedControl(items: items)
control.selectedSegmentIndex = 0
control.tintColor = UIColor.honePalette.accent
let font = UIFont.systemFont(ofSize: 12)
control.setTitleTextAttributes([NSFontAttributeName: font], for: .normal)
return control
}
func prepareCollectionView(){
collectionView?.backgroundColor = UIColor.white
collectionView?.alwaysBounceVertical = true
collectionView?.register(sessionsInfo.self, forCellWithReuseIdentifier: "cellId")
}
// return of the number per item per section
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 5
}
//this is when the collection is clicked
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
let indexPath = collectionView.indexPathsForSelectedItems
print("this is index path:", indexPath)
}
// this is the cell of the collection returning initialized with the SessionsInfo
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let myCell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellId", for: indexPath) as? sessionsInfo
myCell?.sessionLabel.text = "cell \(indexPath.row)"
return myCell!
}
// this is when the size of the cell returns
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: view.frame.width - 10, height: 80)
}
// return supplementary view
override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "header", for: indexPath)
let label = UILabel(frame: headerView.bounds)
label.text = "Top View"
label.font = UIFont(name: "helvetica", size: 12)
label.textAlignment = .center
headerView.addSubview(label)
//headerView.headerLabel.text = "header"
return headerView
}
func handleLogout(){
BaseServices.baseServices.signOut()
present(LoginViewController(), animated: true, completion: nil)
}
}
class headerInfo : UICollectionReusableView{
override init(frame: CGRect) {
super.init(frame: frame)
setupHeader()
}
var headerLabel : UILabel = {
let label = UILabel()
label.text = "HEADER"
label.translatesAutoresizingMaskIntoConstraints = false
return label
}()
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func setupHeader(){
backgroundColor = UIColor.honePalette.raindrops
addSubview(headerLabel)
addConstraints(NSLayoutConstraint.constraints( withVisualFormat: "H:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0":headerLabel]))
addConstraints(NSLayoutConstraint.constraints( withVisualFormat: "V:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0":headerLabel]))
}
}
class sessionsInfo: UICollectionViewCell {
override init(frame: CGRect) {
super.init(frame: frame)
setupSessions()
}
var sessionLabel : UILabel = {
let label = UILabel()
label.text = "sessionView"
label.translatesAutoresizingMaskIntoConstraints = false
return label
}()
var sessionTimeLabel : UILabel = {
let label = UILabel()
label.text = ""
label.translatesAutoresizingMaskIntoConstraints = false
return label
}()
var sessionLocationLabel : UILabel = {
let label = UILabel()
label.text = ""
label.translatesAutoresizingMaskIntoConstraints = false
return label
}()
func setupSessions(){
backgroundColor = UIColor.honePalette.raindrops
addSubview(sessionLabel)
addConstraints(NSLayoutConstraint.constraints( withVisualFormat: "H:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0":sessionLabel]))
addConstraints(NSLayoutConstraint.constraints( withVisualFormat: "V:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0":sessionLabel]))
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}

Answer 1

I tried your code in a new project, and you are missing two key steps: registering the supplementary view and setting the size of your header.
In your prepareCollectionView function, you also need to register the header view:
collectionView?.register(headerInfo.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "header")
You also need to implement another delegate function giving the size of your header view:
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width: 100, height: 100) // fix to be your intended size
}
Here is proof that it works. (I didn't have access to your custom colors, which is why everything is orange and gray.)