UICollectionView method (collectionView cellForItemAt indexPath ) not called - ios

I am trying to make a custom bar menu using UICollectionView,the problem is that cells not showed method collectionView cellForItemAt indexPath not called.
My code so far:
import UIKit
private let reuseIdentifier = "Cell"
class MenuBar : UIView ,UICollectionViewDelegate,UICollectionViewDataSource,UICollectionViewDelegateFlowLayout{
lazy var collectionView : UICollectionView = {
let layout = UICollectionViewLayout()
let cv = UICollectionView(frame: .zero , collectionViewLayout : layout)
cv.dataSource = self
cv.delegate = self
cv.backgroundColor = UIColor.white
return cv
}()
override init(frame: CGRect) {
super.init(frame: frame)
collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)
addSubview(collectionView)
setUpCollectionViewConstraints()
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 2
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath)
cell.backgroundColor = UIColor.red
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: frame.height/2, height: frame.height)
}
fileprivate func setUpCollectionViewConstraints() {
collectionView.translatesAutoresizingMaskIntoConstraints = false
let horizontalConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:|[cv]|", options: NSLayoutFormatOptions.alignAllCenterY, metrics: nil, views: ["cv" : collectionView])
let verticalConstraints = NSLayoutConstraint.constraints(withVisualFormat:"V:|[cv]|", options: NSLayoutFormatOptions.alignAllCenterY, metrics: nil, views: ["cv" : collectionView])
addConstraints(horizontalConstraints)
addConstraints(verticalConstraints)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}

Please check :
Your layout should be like below.
You used UICollectionViewLayout.
You have to use UICollectionViewFlowLayout
let layout = UICollectionViewFlowLayout()

It looks like the datasource has something wrong.
Your MenuBar is on a ViewController right?
You may not set collectionView's datasource to MenuBar(Delegate too). You might set collectionView's datasource to a ViewController.

Related

How to change the position of cells in a collection view tin constraints?

I have 4 cells within a collection view, but with the constraints added they appear near the upper right corner of the view. Here is the code for those cells:
class TopHomeMenuBar: UIView, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {
lazy var collectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
cv.backgroundColor = UIColor.systemGreen
cv.dataSource = self
cv.delegate = self
return cv
}()
let cellId = "cellId"
override init(frame: CGRect) {
super.init(frame: frame)
collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: cellId)
addSubview(collectionView)
addConstraintsWithFormat("H:|[v0]|", views: collectionView)
addConstraintsWithFormat("V:|[v0]|", views: collectionView)
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 4
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath)
cell.backgroundColor = .red
return cell
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
Is there a way with those constraints to change the y coordinate of the cells so they appear near the bottom of the collection view?
If the UICollectionView is static you can shift the cells to the bottom by losing the top constraint and giving it a constant height constraint and constraining it to the bottom. Here's how:
Modify this:
addConstraintsWithFormat("H:|[v0]|", views: collectionView)
addConstraintsWithFormat("V:|[v0]|", views: collectionView)
To this:
addConstraintsWithFormat("H:|[v0]|", views: collectionView)
addConstraintsWithFormat("V:[v0(100)]|", views: collectionView)

Loop of UITableViews with each UITableView have different data?

I want to build a todo app where you can swipe through different days (UITableViews). The amount of days (UITableViews) needs to be dynamic in a variable. I want each tableview in the loop show different data from an array.
For example with this array:
var testArray = [
["Day0-0","Day0-1","Day0-2"],
["Day1-0","Day1-1","Day1-2"],
["Day2-0","Day2-1","Day2-2"]
]
Then I need to select my data for example like this: testArray[indexPath of tableviews][0]
What is the best way to do this?
You can use a collectionview and add tableview in collectionview cell.
CollectionCell.swift
class CollectionCell: UICollectionViewCell {
let tableView = UITableView()
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
commonInit()
}
func commonInit() {
tableView.backgroundColor = .white
tableView.translatesAutoresizingMaskIntoConstraints = false
addSubview(tableView)
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[tableView]|", options: [], metrics: nil, views: ["tableView":tableView]))
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[tableView]|", options: [], metrics: nil, views: ["tableView":tableView]))
}
}
ViewController.swift
class ViewController: UIViewController {
var testArray = [["Day0-0","Day0-1","Day0-2"], ["Day1-0","Day1-1","Day1-2"], ["Day2-0","Day2-1","Day2-2"]]
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: UICollectionViewFlowLayout())
override func viewDidLoad() {
super.viewDidLoad()
view.backgroundColor = .white
let layout = collectionView.collectionViewLayout as! UICollectionViewFlowLayout
layout.scrollDirection = .horizontal
collectionView.delegate = self
collectionView.dataSource = self
collectionView.backgroundColor = .white
collectionView.isPagingEnabled = true
collectionView.translatesAutoresizingMaskIntoConstraints = false
collectionView.register(CollectionCell.self, forCellWithReuseIdentifier: "CollectionCell")
view.addSubview(collectionView)
view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[collectionView]|", options: [], metrics: nil, views: ["collectionView":collectionView]))
view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[collectionView]|", options: [], metrics: nil, views: ["collectionView":collectionView]))
}
}
extension ViewController: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return testArray.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionCell", for: indexPath) as? CollectionCell ?? CollectionCell()
cell.tableView.tag = indexPath.item
cell.tableView.reloadData()
cell.tableView.delegate = self
cell.tableView.dataSource = self
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return collectionView.frame.size
}
}
extension ViewController: UITableViewDelegate, UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return testArray[tableView.tag].count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell") ?? UITableViewCell(style: .default, reuseIdentifier: "Cell")
cell.textLabel?.text = testArray[tableView.tag][indexPath.row]
return cell
}
}
You can nest data structures in any way that makes sense to you.
If you want to have an array of table view data models, create an array of table view data models.
Typically the data model for a table view is either a simple array (for a single-sectioned table view) or an array of arrays, for a sectioned table view.
I agree with #GustafRosenblad's suggestion of using a page view controller as the interface for swiping between pages. It's a perfect for that. Each page would have a table view. You'd use the index of the current page to index into your array of data models, then fetch the data for that page's table view and display it on that page.

UICollectionView keep horizontal list scroll position

I have some horizontal UICollectionViewCell in my UICollectionView.
My problem is that if I scroll the horizontal list in the first cell to another position, the fourth cell will also be at that same position.
Same for the second and the fifth, the third and the sixth...
Also don’t keep horizontal scroll position from portrait to landscape or opposite.
Is there a way for the UICollectionView in the cells to keep their position?
Update 2:
I know i have to save inner horizontal collection view content offsets in an array. I read about that in link below, but in the below link they want to achieve this in UITableView and UIScrollView. And i want to achieve this in UICollectionView inside UICollectionViewController.
Scroll View in UITableViewCell won't save position
Updated 1:
https://imgur.com/a/F8EGsTx
ViewController.swift
import UIKit
class ViewController: UICollectionViewController, UICollectionViewDelegateFlowLayout {
let cellId = "cellId"
override func viewDidLoad() {
super.viewDidLoad()
collectionView?.backgroundColor = .white
collectionView?.register(CategoryCell.self, forCellWithReuseIdentifier: cellId)
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! CategoryCell
cell.nameLabel.text = "Horizontal list #\(indexPath.item)"
return cell
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 10
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: view.frame.width, height: 150)
}
}
CategoryCell.swift
import UIKit
class CategoryCell: UICollectionViewCell, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {
let cellId = "categoryId"
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
var nameLabel: UILabel = {
let label = UILabel()
label.text = "Horizontal list #1"
label.font = UIFont.systemFont(ofSize: 16)
label.translatesAutoresizingMaskIntoConstraints = false
return label
}()
let appsCollectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
collectionView.translatesAutoresizingMaskIntoConstraints = false
collectionView.backgroundColor = .white
return collectionView
}()
let dividerLineView: UIView = {
let view = UIView()
view.backgroundColor = UIColor(white: 0.4, alpha: 0.4)
view.translatesAutoresizingMaskIntoConstraints = false
return view
}()
func setupViews() {
addSubview(appsCollectionView)
addSubview(dividerLineView)
addSubview(nameLabel)
appsCollectionView.dataSource = self
appsCollectionView.delegate = self
appsCollectionView.register(AppCell.self, forCellWithReuseIdentifier: cellId)
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-14-[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": nameLabel]))
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-14-[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": dividerLineView]))
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[v0]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": appsCollectionView]))
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[nameLabel(30)][v0][v1(0.5)]|", options: NSLayoutFormatOptions(), metrics: nil, views: ["v0": appsCollectionView, "v1": dividerLineView, "nameLabel": nameLabel]))
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 10
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! AppCell
cell.imageView.backgroundColor = UIColor(hue: CGFloat(indexPath.item) / 20.0, saturation: 0.8, brightness: 0.9, alpha: 1)
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 100, height: frame.height - 32)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
return UIEdgeInsetsMake(0, 14, 0, 14)
}
}
AppCell.swift
import UIKit
class AppCell: UICollectionViewCell {
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
let imageView: UIImageView = {
let iv = UIImageView()
iv.contentMode = .scaleAspectFill
iv.layer.cornerRadius = 16
iv.layer.masksToBounds = true
return iv
}()
func setupViews() {
addSubview(imageView)
imageView.frame = CGRect(x: 0, y: 0, width: frame.width, height: frame.width)
}
}
I finally got it :)
Thanks to 3 years old project! from irfanlone
https://github.com/irfanlone/Collection-View-in-a-collection-view-cell
It's works and support interface orientation too, but need some optimization.
For example if you scroll to the right and then scroll down fast and then scroll back to top the cell have a extra margin from the right edge! Also have some issue with interface orientation.
If anyone have a complete version please share that, thanks.
For anyone who may be interested, Add the following code in the specified files.
ViewController.swift
var storedOffsets = [Int: CGFloat]()
override func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
guard let collectionViewCell = cell as? CategoryCell else { return }
collectionViewCell.collectionViewOffset = storedOffsets[indexPath.row] ?? 0
}
override func collectionView(_ collectionView: UICollectionView, didEndDisplaying cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
guard let collectionViewCell = cell as? CategoryCell else { return }
storedOffsets[indexPath.row] = collectionViewCell.collectionViewOffset
}
CategoryCell.swift
var collectionViewOffset: CGFloat {
set {
appsCollectionView.contentOffset.x = newValue
}
get {
return appsCollectionView.contentOffset.x
}
}
#zahaniza thank You for answer, in addition to Your code
If You are using multiple sections the code will look like
ViewController.swift
var storedOffsets = [IndexPath: CGFloat]()
override func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
guard let collectionViewCell = cell as? CategoryCell else { return }
collectionViewCell.collectionViewOffset = storedOffsets[indexPath] ?? 0
}
override func collectionView(_ collectionView: UICollectionView, didEndDisplaying cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
guard let collectionViewCell = cell as? CategoryCell else { return }
storedOffsets[indexPath] = collectionViewCell.collectionViewOffset
}
Inner collection views get reused. If you want to keep the scroll position for each horizontal collection view you must keep an array of scroll positions in your UIViewController and update it when inner collection view gets scrolled. Then when reusing outer collection view cells you can reset the scroll position in collectionView(collectionView:, cellForItemAt indexPath:) method.
Your outer collection view population method should look something like this:
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! CategoryCell
cell.nameLabel.text = "Horizontal list #\(indexPath.item)"
cell.scrollPosition = this.scrollPositions[indexPath.item]
return cell
}
From the answer of #zahaniza, this code fixes his issue and works well for iPhone X :
var storedOffsets = [Int: CGFloat]()
override func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
guard let collectionViewCell = cell as? CategoryCell,
let innerCollectionView = collectionViewCell.collectionView else { return }
// Default collection offset is -adjustedContentInset.left and not 0
let minOffset = -innerCollectionView.adjustedContentInset.left
let maxOffset = innerCollectionView.contentSize.width - innnerCollectionView.frame.width
maxOffset += innerCollectionView.adjustedContentInset.left
if let offset = storedOffsets[indexPath.row] {
innerCollectionView.contentOffset = CGPoint(max(minOffset, miin(maxOffset, offset.x)), 0)
} else {
innerCollectionView.contentOffset = CGPoint(minOffset, 0);
}
collectionViewCell.collectionViewOffset = storedOffsets[indexPath.row] ?? 0
}
override func collectionView(_ collectionView: UICollectionView, didEndDisplaying cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
guard let collectionViewCell = cell as? CategoryCell else { return }
storedOffsets[indexPath.row] = collectionViewCell.collectionView.contentOffset
}

Nest a UICollectionView inside a UIVIew programmatically

I am attempting to get a UICollectionView to be inside a UIView as the framework I'm using requires a UIView to be returned. I have looked at this question: How do I add a UICollectionView to a UIView as a subview? and Adding UICollectionView inside UIView without Storyboards but not sure how to get it to work.
I have a attempted it like this:
class TopView : UIView, UICollectionViewDataSource, UICollectionViewDelegate {
override init(frame: CGRect) {
super.init(frame: frame)
self.backgroundColor = .red
addSubview(collectionView)
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
lazy var collectionView : UICollectionView = {
let layout = UICollectionViewFlowLayout()
let cv = UICollectionView(frame: CGRect.zero, collectionViewLayout: layout)
cv.translatesAutoresizingMaskIntoConstraints = false
cv.delegate = self
cv.dataSource = self
cv.register(HeaderCell.self, forCellWithReuseIdentifier: "HeaderCell")
cv.backgroundColor = .yellow
return cv
}()
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "HeaderCell", for: indexPath) as! HeaderCell
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: self.collectionView.frame.width, height: 200)
}
func collectionView(_ collectionView: UICollectionView, numberOfSections section: Int) -> Int {
return 1
}
}
But I'm getting a blank screen.
Update:
This is how I add the TopView to a UIViewController:
class MainViewController: UIViewController {
var mainView = TopView()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(mainView)
}
}
I get just a black screen.
TopView.swift
class TopView : UIView, UICollectionViewDataSource, UICollectionViewDelegate {
lazy var collectionView : UICollectionView = {
let layout = UICollectionViewFlowLayout()
let cv = UICollectionView(frame: CGRect.zero, collectionViewLayout: layout)
//If you set it false, you have to add constraints.
cv.translatesAutoresizingMaskIntoConstraints = false
cv.delegate = self
cv.dataSource = self
cv.register(HeaderCell.self, forCellWithReuseIdentifier: "HeaderCell")
cv.backgroundColor = .yellow
return cv
}()
override init(frame: CGRect) {
super.init(frame: frame)
self.backgroundColor = .red
addSubview(collectionView)
//Add constraint
collectionView.leadingAnchor.constraint(equalTo: leadingAnchor).isActive = true
collectionView.trailingAnchor.constraint(equalTo: trailingAnchor).isActive = true
collectionView.topAnchor.constraint(equalTo: topAnchor).isActive = true
collectionView.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
func collectionView(_ collectionView: UICollectionView, numberOfSections section: Int) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 30
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "HeaderCell", for: indexPath) as! HeaderCell
cell.backgroundColor = .cyan
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: self.collectionView.frame.size.width, height: 200)
}
}
ViewController.swift
lazy var topView: TopView = {
let tv = TopView()
tv.translatesAutoresizingMaskIntoConstraints = false
return tv
}()
func addTopView() {
view.addSubview(topView)
topView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
topView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
topView.topAnchor.constraint(equalTo: view.topAnchor, constant: 300).isActive = true
topView.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true
topView.heightAnchor.constraint(equalToConstant: 200).isActive = true
}
Call addTopView() from viewDidLoad()

referenceSizeForHeaderInSection method error

I am trying to add a headerCell to a UICollectionView and am trying to call the referenceSizeForHeaderInSection method. I have created a collectionViewCell (ProfileCell) and it builds correctly, until I call the the referenceSizeForHeaderInSection method, then it crashes...not sure why. Thanks in advance for any and all help!
// UICollectionViewCell class *******
class ProfileCell: UICollectionViewCell {
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
}
let wordLabel: UILabel = {
let label = UILabel()
label.text = "test test test"
label.translatesAutoresizingMaskIntoConstraints = false
return label
}()
func setupViews() {
backgroundColor = .red
addSubview(wordLabel)
wordLabel.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
wordLabel.leftAnchor.constraint(equalTo: self.leftAnchor).isActive = true
wordLabel.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
wordLabel.rightAnchor.constraint(equalTo: self.rightAnchor).isActive = true
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
// UIViewController *******
class HomeController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout, FBSDKLoginButtonDelegate {
lazy var collectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
layout.minimumLineSpacing = 0
let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
cv.delegate = self
cv.dataSource = self
cv.isPagingEnabled = true
return cv
}()
let cellId = "cellId"
let headerId = "headerId"
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(collectionView)
// use autolayout instead
collectionView.anchorToTop(view.topAnchor, left: view.leftAnchor, bottom: view.bottomAnchor, right: view.rightAnchor)
collectionView.backgroundColor = .white
collectionView.register(ProfileCell.self, forCellWithReuseIdentifier: cellId)
collectionView.register(UICollectionViewCell.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: headerId)
fileprivate func registerCells() {
collectionView.register(ProfileCell.self, forCellWithReuseIdentifier: cellId)
}
// set up collectionView
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 4
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath)
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: view.frame.width, height: 150)
}
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
let header = collectionView.dequeueReusableCell(withReuseIdentifier: headerId, for: indexPath)
return header
}
// crashes when I call this method
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width: view.frame.width, height: 50)
}
}

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