I have created a TableViewController and made a header on it. I added a UICollectionViewController into the header. When I am tapping on cells, they are disappearing. Did anyone have the same issue?
import UIKit
class HeaderController {
override init(frame: CGRect) {
super.init(frame: frame)
let categoryCollectionController = CategoryCollectionController(collectionViewLayout: UICollectionViewFlowLayout())
let categoryView = categoryCollectionController.view!
categoryView.translatesAutoresizingMaskIntoConstraints = false
addSubview(categoryView)
NSLayoutConstraint.activate([
categoryView.leftAnchor.constraint(equalTo: leftAnchor),
categoryView.rightAnchor.constraint(equalTo: rightAnchor),
categoryView.topAnchor.constraint(equalTo: topAnchor),
categoryView.bottomAnchor.constraint(equalTo: bottomAnchor)
])
}
}
class CategoryCollectionController: UICollectionViewController, UICollectionViewDelegateFlowLayout {
let cellID = "UID"
override func viewDidLoad() {
super.viewDidLoad()
collectionView.backgroundColor = .red
collectionView.register(CellCategory.self, forCellWithReuseIdentifier: cellID)
if let layout = collectionViewLayout as? UICollectionViewFlowLayout {
layout.scrollDirection = .horizontal
}
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 10
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellID, for: indexPath) as! CellCategory
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 100, height: 100)
}
}
You can fix this by keeping a reference to the collection view on the header.
Without keeping a reference to the collection view (and not just it's weak view property you've added as a subview), it will be thrown out once init exits scope.
For example:
class HeaderController: UIView {
let categoryCollectionController = CategoryCollectionController(collectionViewLayout: UICollectionViewFlowLayout())
override init(frame: CGRect) {
super.init(frame: frame)
let categoryView = categoryCollectionController.view!
categoryView.translatesAutoresizingMaskIntoConstraints = false
addSubview(categoryView)
NSLayoutConstraint.activate([
categoryView.leftAnchor.constraint(equalTo: leftAnchor),
categoryView.rightAnchor.constraint(equalTo: rightAnchor),
categoryView.topAnchor.constraint(equalTo: topAnchor),
categoryView.bottomAnchor.constraint(equalTo: bottomAnchor)
])
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
Related
I am trying to create a similar layout to the App store. I have got one collection view that is vertical and inside of it each row is another collection view that is horizontal.
I am trying to use dynamic height so the cell can increase its height based on the content inside. However that never works, it only works when i use sizeForItemAt function to explicitly set it. I would like to also be able to control the width
I have looked at many previous questions such as: UICollectionView, full width cells, allow autolayout dynamic height? however no answer worked for me.
I am really confused on what i am doing wrong.
import UIKit
class HomeViewController: UICollectionViewController {
public override func viewDidLoad() {
super.viewDidLoad()
let collectionViewLayout = UICollectionViewFlowLayout()
collectionViewLayout.scrollDirection = .vertical
collectionViewLayout.estimatedItemSize = UICollectionViewFlowLayout.automaticSize
collectionView.collectionViewLayout = collectionViewLayout
collectionView.translatesAutoresizingMaskIntoConstraints = false
collectionView?.register(HorizontalCollectionView.self, forCellWithReuseIdentifier: HorizontalCollectionView.reuseIdentifier)
}
public override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 1
}
public override func numberOfSections(in collectionView: UICollectionView) -> Int {
return 4
}
public override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: HorizontalCollectionView.reuseIdentifier, for: indexPath) as? HorizontalCollectionView {
return cell
}
return UICollectionViewCell()
}
}
HorizontalCollectionView.swift
import UIKit
class HorizontalCollectionView: UICollectionViewCell, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {
static let reuseIdentifier = "HorizontalCollectionView"
var cellSpancolumns: CGFloat?
override init(frame: CGRect) {
super.init(frame: frame)
collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "cell")
collectionView.delegate = self
collectionView.dataSource = self
addSubview(collectionView)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented - Storyboards are not used.")
}
lazy var collectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
layout.estimatedItemSize = UICollectionViewFlowLayout.automaticSize
let collectionView = UICollectionView(frame: bounds, collectionViewLayout: layout)
collectionView.translatesAutoresizingMaskIntoConstraints = false
collectionView.showsHorizontalScrollIndicator = false
return collectionView
}()
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 3
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath)
if (indexPath as NSIndexPath).section == 0 {
cell.backgroundColor = UIColor.blue
} else {
cell.backgroundColor = UIColor.red
}
return cell
}
}
I am currently working on a horizontal gallery scroll view. I have decided to use UICollectionView with horizontal paging enabled. It almost works great... expect on rotation the collection view cells are not centred (see screenshot attached), where red is the first cell and yellow is the second one.
It usually works fine on the first rotation but then just messes up :D
This is the code I have for setting up the class:
class GalleryScrollView: UIView {
private var collectionView: UICollectionView!
private var layout: UICollectionViewFlowLayout!
override init(frame: CGRect) {
super.init(frame: frame)
setupView()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
setupView()
}
override func layoutSubviews() {
layout.invalidateLayout()
}
private func setupView() {
layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
collectionView = UICollectionView(frame: self.frame,
collectionViewLayout: layout)
collectionView.register(UINib(nibName: "PhotoGalleryCell", bundle: nil), forCellWithReuseIdentifier: "photoGalleryCell")
collectionView.isPagingEnabled = true
collectionView.contentInsetAdjustmentBehavior = .never
collectionView.dataSource = self
collectionView.delegate = self
collectionView.autoresizingMask = .flexibleWidth
collectionView.translatesAutoresizingMaskIntoConstraints = false
collectionView.backgroundColor = .green
self.addSubview(collectionView)
NSLayoutConstraint.activate([
collectionView.leadingAnchor.constraint(equalTo: self.leadingAnchor),
collectionView.trailingAnchor.constraint(equalTo: self.trailingAnchor),
collectionView.topAnchor.constraint(equalTo: self.topAnchor),
collectionView.bottomAnchor.constraint(equalTo: self.bottomAnchor)
])
collectionView.reloadData()
}
}
Followed by the collection view setup:
extension GalleryScrollView: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "photoGalleryCell", for: indexPath) as? PhotoGalleryCell else {
return UICollectionViewCell()
}
if indexPath.item == 0 {
cell.backgroundColor = .red
} else {
cell.backgroundColor = .yellow
}
return cell
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
2
}
func collectionView(_ collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
sizeForItemAt indexPath: IndexPath) -> CGSize {
return self.frame.size
}
I tried playing around with func collectionView(_ collectionView: UICollectionView, targetContentOffsetForProposedContentOffset proposedContentOffset: CGPoint) -> CGPoint { but for some reason the func was never called.
Did anyone else run into this problem? I saw a lot of topics in objective c threads, not much in swift. I am also somewhat struggling to understand why this is happening, so just understanding the problem would be very helpful. Thank you!
You don't seem to have handled rotations. You need to reloadData when a rotation occurs. You'll get the event in UIViewController from there you can call reloadData on the instance of your UICollectionView.
class GalleryViewController: UIViewController {
//...
var galleryScrollView: GalleryScrollView
//...
override func willTransition(to newCollection: UITraitCollection, with coordinator: UIViewControllerTransitionCoordinator) {
super.willTransition(to: newCollection, with: coordinator)
galleryScrollView.collectionViewLayout.invalidateLayout()
}
//...
}
Then in GalleryScrollView:
class GalleryScrollView: UIView {
var currentVisibleIndexPath = IndexPath(row: 0, section: 0)
//....
}
extension GalleryScrollView: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
//...
func collectionView(_ collectionView: UICollectionView, targetContentOffsetForProposedContentOffset proposedContentOffset: CGPoint) -> CGPoint {
let attributes = collectionView.layoutAttributesForItem(at: currentVisibleIndexPath)
let newOriginForOldIndex = attributes?.frame.origin
return newOriginForOldIndex ?? proposedContentOffset
}
func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
let center = CGPoint(x: scrollView.contentOffset.x + (scrollView.frame.width / 2), y: (scrollView.frame.height / 2))
if let indexPath = self.screenView.indexPathForItem(at: center) {
currentVisibleIndexPath = indexPath
}
}
}
For some reasons I cannot properly display some items from a collection inside an tableview cell when using Xcode 10 beta. I tried all I know for the last 4 days.
I made a small project sample to see what my issue is.
Full code is here if someone wants to run it locally: https://github.com/adrianstanciu24/CollectionViewInsideUITableViewCell
I first add an table view with 2 different resizable cells, first cell has the collection view and a label:
class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {
#IBOutlet weak var tableView: UITableView!
override func viewDidLoad() {
super.viewDidLoad()
tableView.delegate = self
tableView.dataSource = self
tableView.estimatedRowHeight = 44
tableView.rowHeight = UITableView.automaticDimension
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 2
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if indexPath.row == 0 {
let cell = tableView.dequeueReusableCell(withIdentifier: "collCell") as! CollectionTableViewCell
cell.collectionView.collectionViewLayout.invalidateLayout()
return cell
} else {
let cell = tableView.dequeueReusableCell(withIdentifier: "normalCell")!
return cell
}
}
}
Here is the cell with collection view defined. This also has a height constraint which I updated in layoutSubviews:
class CollectionTableViewCell: UITableViewCell, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout, UICollectionViewDelegate {
#IBOutlet weak var collectionView: UICollectionView!
#IBOutlet weak var collectionViewHeightConstraint: NSLayoutConstraint!
override func awakeFromNib() {
super.awakeFromNib()
collectionView.delegate = self
collectionView.dataSource = self
if let layout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout {
layout.estimatedItemSize = UICollectionViewFlowLayout.automaticSize
}
}
override func layoutSubviews() {
super.layoutSubviews()
collectionViewHeightConstraint.constant = collectionView.collectionViewLayout.collectionViewContentSize.height
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 10
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "taskCell", for: indexPath as IndexPath) as! TaskCollectionViewCell
cell.name.text = "Task_" + String(indexPath.row)
return cell
}
}
Below is a screenshot with the collection view constraint and how the storyboard looks:
And this is how it looks when running:
The cells are squashed and label on top disappears. What I want is the collection view should grow to show all elements and also making table view cell to resize, but that is not happening at the moment and I can't figure out where the issue is.
If you want the following output:
Code
ViewController:
class ViewController: UIViewController {
let list = [String](repeating: "Label", count: 10)
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(tableView)
tableView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
tableView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
tableView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
tableView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
tableView.trailingAnchor.constraint(equalTo: view.trailingAnchor)
])
tableView.reloadData()
}
public lazy var tableView: UITableView = { [unowned self] in
let v = UITableView.init(frame: .zero)
v.delegate = self
v.dataSource = self
v.estimatedRowHeight = 44
v.rowHeight = UITableViewAutomaticDimension
v.register(TableCell.self, forCellReuseIdentifier: "TableCell")
return v
}()
}
extension ViewController: UITableViewDelegate{
}
extension ViewController: UITableViewDataSource{
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return list.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "TableCell", for: indexPath) as! TableCell
cell.label.text = "\(list[indexPath.row]) \(indexPath.row)"
return cell
}
}
TableCell:
class TableCell: UITableViewCell{
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
commonInit()
}
override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
commonInit()
}
func commonInit(){
contentView.addSubview(label)
contentView.addSubview(collectionView)
updateConstraints()
}
override func updateConstraints() {
label.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
label.topAnchor.constraint(equalTo: topAnchor),
label.leadingAnchor.constraint(equalTo: leadingAnchor),
label.trailingAnchor.constraint(equalTo: trailingAnchor)
])
collectionView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
collectionView.topAnchor.constraint(equalTo: label.bottomAnchor),
collectionView.leadingAnchor.constraint(equalTo: leadingAnchor),
collectionView.bottomAnchor.constraint(equalTo: bottomAnchor),
collectionView.trailingAnchor.constraint(equalTo: trailingAnchor),
])
super.updateConstraints()
}
let list = [String](repeating: "Task_", count: 10)
public let label: UILabel = {
let v = UILabel()
v.textAlignment = .center
return v
}()
public lazy var collectionView: UICollectionView = { [unowned self] in
let layout = UICollectionViewFlowLayout()
layout.minimumLineSpacing = 0
layout.minimumInteritemSpacing = 0
let v = UICollectionView(frame: .zero, collectionViewLayout: layout)
v.register(CollectionCell.self, forCellWithReuseIdentifier: "CollectionCell")
v.delegate = self
v.dataSource = self
v.isScrollEnabled = false
return v
}()
override func sizeThatFits(_ size: CGSize) -> CGSize {
let collectionCellHeight = 50
let rows = list.count / 5 // 5: items per row
let labelHeight = 20 // you can calculate String height
let height = CGFloat((collectionCellHeight * rows) + labelHeight)
let width = contentView.frame.size.width
return CGSize(width: width, height: height)
}
}
extension TableCell: UICollectionViewDataSource{
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return list.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionCell", for: indexPath) as! CollectionCell
cell.label.text = "\(list[indexPath.item])\(indexPath.item)"
return cell
}
}
extension TableCell: UICollectionViewDelegate{
}
extension TableCell: UICollectionViewDelegateFlowLayout{
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: collectionView.frame.width/5, height: 50)
}
}
CollectionCell
class CollectionCell: UICollectionViewCell{
let padding: CGFloat = 5
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
commonInit()
}
func commonInit(){
backgroundColor = .yellow
contentView.addSubview(label)
updateConstraints()
}
override func updateConstraints() {
label.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
label.topAnchor.constraint(equalTo: topAnchor, constant: padding),
label.leadingAnchor.constraint(equalTo: leadingAnchor, constant: padding),
label.trailingAnchor.constraint(equalTo: trailingAnchor, constant: -padding),
label.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -padding)
])
super.updateConstraints()
}
public let label: UILabel = {
let v = UILabel()
v.textColor = .darkText
v.minimumScaleFactor = 0.5
v.numberOfLines = 1
return v
}()
}
Made with Swift 5.3 and tested on iOS 14, the follow it should work just copy and paste 😉:
TableViewController.swift
import UIKit
import SnapKit
class TableViewController: UIViewController {
private let tableView: UITableView = UITableView()
private let tableViewCellId = "TableViewCell"
override func viewDidLoad() {
super.viewDidLoad()
setupUI()
}
}
// MARK: - Setup UIs
extension TableViewController {
private func setupUI() {
tableView.delegate = self
tableView.dataSource = self
tableView.register(TableViewCell.self, forCellReuseIdentifier: tableViewCellId)
view.addSubview(tableView)
tableView.snp.makeConstraints {
$0.edges.equalToSuperview()
}
}
}
// MARK: - Delegate & DataSource
extension TableViewController: UITableViewDelegate, UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 5
}
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: tableViewCellId) as! TableViewCell
cell.backgroundColor = .white
return cell
}
func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
return 100
}
}
TableViewCell.swift
import UIKit
import SnapKit
class TableViewCell: UITableViewCell {
private let list = [String](repeating: "Row ", count: 10)
private let collectionViewLayout = UICollectionViewFlowLayout()
lazy private var collectionView: UICollectionView = UICollectionView(frame: .zero, collectionViewLayout: collectionViewLayout)
override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
super.init(style: style, reuseIdentifier: reuseIdentifier)
}
override func layoutSubviews() {
setupUI()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
}
// MARK: - UI Setup
extension TableViewCell {
private func setupUI() {
// layout.minimumLineSpacing = 5
// layout.minimumInteritemSpacing = 5
collectionViewLayout.scrollDirection = .horizontal
collectionView.backgroundColor = .clear
collectionView.showsHorizontalScrollIndicator = false
collectionView.register(CollectionViewCell.self, forCellWithReuseIdentifier: "CollectionCell")
collectionView.delegate = self
collectionView.dataSource = self
addSubview(collectionView)
collectionView.snp.makeConstraints {
$0.edges.equalToSuperview()
}
}
}
extension TableViewCell: UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return list.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CollectionCell", for: indexPath) as! CollectionViewCell
cell.titleLabel.text = "\(list[indexPath.item])\(indexPath.item)"
return cell
}
}
extension TableViewCell: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: collectionView.frame.width / 5, height: 100)
}
}
CollectionViewCell.swift
import UIKit
class CollectionViewCell: UICollectionViewCell {
var titleLabel: UILabel = UILabel()
override init(frame: CGRect) {
super.init(frame: frame)
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func layoutSubviews() {
setupUI()
}
}
// MARK: - UI Setup
extension CollectionViewCell {
private func setupUI() {
titleLabel.font = UIFont(name: "HelveticaNeue", size: 20)
titleLabel.textColor = .white
titleLabel.translatesAutoresizingMaskIntoConstraints = false
titleLabel.backgroundColor = .systemGreen
titleLabel.textAlignment = .center
addSubview(titleLabel)
titleLabel.snp.makeConstraints {
$0.centerX.centerY.equalToSuperview()
$0.height.equalTo(60)
$0.width.equalTo(150)
}
}
}
If your desired output is following
Then replace your code of collectionview with this
class CollectionTableViewCell: UITableViewCell, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout, UICollectionViewDelegate {
#IBOutlet weak var collectionView: UICollectionView!
#IBOutlet weak var collectionViewHeightConstraint: NSLayoutConstraint!
var arrForString:[String] = ["Task_0","Task_1","Task_3","Task_4","Task_5","Task_6","Task_7","Task_8","Task_9","Task_10"]
override func awakeFromNib() {
super.awakeFromNib()
collectionView.delegate = self
collectionView.dataSource = self
if let layout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout {
layout.estimatedItemSize = UICollectionViewFlowLayout.automaticSize
}
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return arrForString.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "taskCell", for: indexPath as IndexPath) as! TaskCollectionViewCell
cell.name.text = arrForString[indexPath.row]
cell.layoutIfNeeded()
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
//we are just measuring height so we add a padding constant to give the label some room to breathe!
var padding: CGFloat = 10.0
var height = 10.0
height = Double(estimateFrameForText(text: arrForString[indexPath.row]).height + padding)
return CGSize(width: 50, height: height)
}
private func estimateFrameForText(text: String) -> CGRect {
//we make the height arbitrarily large so we don't undershoot height in calculation
let height: CGFloat = 120
let size = CGSize(width: 50, height: height)
let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
let attributes = [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 18, weight: UIFont.Weight.light)]
return NSString(string: text).boundingRect(with: size, options: options, attributes: attributes, context: nil)
}
}
feel free to ask.
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()
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)
}
}