I have this collection view inside my collection view cell, of which I will populate with more cells. I'm currently trying to update the height of the UICollectionView upon any editing events to the inner cells text field.
This currently works when I load the page, click into the field and then scroll. However, if I load the page, scroll first and then click into the field, it doesn't work but I'm unsure why. I can't see anything that is running differently.
Any help would be appreciated. Thanks.
import UIKit
class MyCollectionViewCell: UICollectionViewCell {
var heightAnchor: NSLayoutConstraint?
var collectionView: UICollectionView!
static let reuseIdentifier: String = "MyCollectionViewCell"
override func awakeFromNib() {
super.awakeFromNib()
var layout: UICollectionViewLayout = UICollectionViewLayout()
collectionView = UICollectionView(frame: contentView, collectionViewLayout: layout)
collectionView.delegate = self
collectionView.dataSource = self
collectionView.isScrollEnabled = false
self.contentView.addSubview(collectionView)
heightAnchor = collectionView.heightAnchor.constraint(equalToConstant: 600)
heightAnchor?.isActive = true
collectionView.anchorViewPosition(parent: self.contentView, leading: .zero, top: .zero, bottom: .zero)
collectionView.register(UINib(nibName: "MyInnerCollectionViewCell", bundle: nil), forCellWithReuseIdentifier: MyInnerCollectionViewCell.reuseIdentifier)
}
override func layoutSubviews() {
super.layoutSubviews()
collectionview.widthAnchor.constraint(equalToConstant: 288).isActive = true
}
#objc func updateCollectionViewSize() {
heightAnchor?.constant = 200
}
}
extension MyCollectionViewCell: UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "MyInnerCollectionViewCell", for: indexPath) as? MyInnerCollectionViewCell
cell?.field.addTarget(self, action: #selector(updateCollectionViewSize()), for: .allEditingEvents)
return cell!
}
}
Related
I am just testing the code to see if it can load the collection view. But id doesn't show anything. Please look at the code below and let me know where I am wrong.
import UIKit
private let reuseIdentifier = "Cell"
class FeedController: UICollectionViewController {
//MARK: - Lifecycle
override func viewDidLoad() {
super.viewDidLoad()
configureUI()
collectionView.dataSource = self
collectionView.delegate = self
self.collectionView.reloadData()
}
//MARK: - Helpers
func configureUI() {
collectionView.backgroundColor = .white
collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)
}
}
//MARK:- UICollectionViewDataSource
extension FeedController {
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 5
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath)
cell.backgroundColor = .systemRed
return cell
}
}
extension FeedController: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: view.frame.width, height: 200)
}
}
Set a breakpoint somewhere in viewDidLoad to test if it even calls any code of this class when running the app.
Normally you get an error when you set the dataSource and delegate in a UICollectionViewController, because these are already set by the controller. Because of this, move the extension lines to the main class and remove the extension.
You need to initialize FeedController using public init(collectionViewLayout layout: UICollectionViewLayout) UICollectionViewController initializer, else you have no layout assigned to the UICollectionView.
Wherever you are doing FeedController() you should do FeedController(collectionViewLayout: UICollectionViewFlowLayout()) or some custom UICollectionViewLayout.
I want to make a UICollectionView with the cells the width of the screen, but the height is based on the aspect ratio of the UIImageView inside.
In my current implementation all of the UICollectionViewCell instances are squares and this isn't what I want.
I want to use auto layout somehow to make the size of the image the width of the screen, but the relevant height depends on the aspect ratio of the image used.
Everything is done programatically in code.
My code:
class ViewController: UIViewController {
var data = ["1","2","3","4","5","6","7","8","1","2","3","4","5","6","7","8"]
var collectionView: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
self.collectionView.dataSource = self
self.collectionView.delegate = self
self.collectionView.register(SubclassedCollectionViewCell.self, forCellWithReuseIdentifier: "cell")
self.collectionView.alwaysBounceVertical = true
self.collectionView.backgroundColor = .white
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
}
override func loadView() {
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.itemSize = CGSize(width: UIScreen.main.bounds.size.width - 20, height: UIScreen.main.bounds.size.width / 1)
layout.scrollDirection = .vertical
collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
self.view = collectionView
}
}
extension ViewController: UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
data.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as? SubclassedCollectionViewCell {
let data = self.data[indexPath.item]
cell.setupCell(image: data)
return cell
}
fatalError("Could not dequeue cell")
}
}
with the cell
class SubclassedCollectionViewCell: UICollectionViewCell {
var hotelImageView: UIImageView = {
var hotelView = UIImageView()
hotelView.contentMode = .scaleAspectFill
hotelView.clipsToBounds = true
return hotelView
}()
override init(frame: CGRect) {
super.init(frame: frame)
addSubview(hotelImageView)
hotelImageView.translatesAutoresizingMaskIntoConstraints = false
hotelImageView.topAnchor.constraint(equalTo: topAnchor).isActive = true
hotelImageView.leftAnchor.constraint(equalTo: leftAnchor).isActive = true
hotelImageView.rightAnchor.constraint(equalTo: rightAnchor).isActive = true
hotelImageView.bottomAnchor.constraint(equalTo: bottomAnchor).isActive = true
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func setupCell(image: String) {
if let image : UIImage = UIImage(named: image) {
hotelImageView.image = image
}
}
}
First, calculate the ratio based on the width and multiply by collection view width you can get a new height based on width.
Final Code: Remove itemSize from the loadview function. And calculate height and return item size in sizeForItemAt method.
loadView
override func loadView() {
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
// layout.itemSize = CGSize(width: UIScreen.main.bounds.size.width - 20, height: UIScreen.main.bounds.size.width / 1) <-- Remove this
layout.scrollDirection = .vertical
collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
self.view = collectionView
}
UICollectionViewDelegateFlowLayout
extension ViewController: UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
data.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as? SubclassedCollectionViewCell {
let data = self.data[indexPath.item]
cell.setupCell(image: data)
return cell
}
fatalError("Could not dequeue cell")
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
guard let iamgeData = UIImage(named: self.data[indexPath.item]) else {
return .zero
}
let width = collectionView.bounds.width
let heightOnWidthRatio = iamgeData.size.height / iamgeData.size.width
let height = width * heightOnWidthRatio
return CGSize(width: width, height: height)
}
}
I've added a UICollectionView to a UIControl (which is being called in a UITableViewController section header) and the UICollectionView is appearing (background color shows), but the datasource and delegate seem to be ignored - no cells are showing and a print statement in my dequeueReusableCell function isn't being called (but one in the UIControl init method is. Can you tell me what I'm missing here?
My UIControl:
// Stripped down code
final class My_Control: UIControl {
override init(frame: CGRect) {
super.init(frame: frame)
addSubview(myCV)
}
private let myCV: Custom_CV = {
let cv: Custom_CV = Custom_CV()
return cv
}()
}
My Collection View:
final class Custom_CV: UIControl, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {
override init(frame: CGRect) {
super.init(frame: frame)
addSubview(collectionView)
collectionView.dataSource = self
collectionView.delegate = self
collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: cellIdentifier)
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 10
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell: UICollectionViewCell = collectionView.dequeueReusableCell(withReuseIdentifier: cellIdentifier, for: indexPath)
cell.backgroundColor = .red
print("Building cell") // Not being called
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 72.0, height: 72.0)
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
//
}
private let cellIdentifier: String = "cellIdentifier"
private let collectionView: UICollectionView = {
let layout: UICollectionViewLayout = UICollectionViewLayout()
let collectionView: UICollectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
collectionView.backgroundColor = .white
return collectionView
}()
}
I think I'm missing something obvious, but I don't see it. I'm expecting to see 10 red squares and 10 print statements, but I get nothing there. But as I said - it's definitely being called because the a print statement in My_CV's init was being called, and I can see the .white background for the collectionview in My_Control.
I have a UIcollectionView with images. When I rotate the screen, the cells do not resize as expected. I have tried adding collectionView.collectionViewLayout.invalidateLayout() to the viewDidLayoutSubviews() - but this only causes a crash. Please can someone advise?
I have a UIcollectionView with images. When I rotate the screen, the cells do not resize as expected. I have tried adding collectionView.collectionViewLayout.invalidateLayout() to the viewDidLayoutSubviews() - but this only causes a crash. Please can someone advise?
Portrait:
Landdscape:
class GridPicksCollectionViewController: UICollectionViewController{
let cellId = "gridyPickCell"
var numCelPerRow: CGFloat = 3
var layout: UICollectionViewFlowLayout!
let borderInset: CGFloat = 3
let interCellSpacing: CGFloat = 3
let spacingBetweenRows: CGFloat = 3
var dataSource = [UIImage]()
var collectionViewWidth: CGFloat!
override func viewDidLoad() {
super.viewDidLoad()
generalSetup()
setUpDateSource()
setupCollectionViewLayout()
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
print("viewDidLayoutSubviews")
// Update collectionViewWidth upon rotation
collectionViewWidth = self.collectionView.frame.width
//collectionView.collectionViewLayout.invalidateLayout() - causes app to crash
}
override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
super.viewWillTransition(to: size, with: coordinator)
print("viewWillTransition")
}
private func generalSetup(){
navigationController?.navigationBar.barTintColor = UIColor.appDarkGreen
navigationItem.title = "Girdy Picks"
let textAttributes = [NSAttributedString.Key.foregroundColor:UIColor.white]
navigationController?.navigationBar.titleTextAttributes = textAttributes
collectionView.backgroundColor = UIColor.white
collectionViewWidth = collectionView.frame.width
// Make sure collectionView is always within the safe area layout
if #available(iOS 11.0, *) {
collectionView?.contentInsetAdjustmentBehavior = .always
}
// Register UICollectionViewCell
collectionView.register(GirdyPickCollectionCell.self, forCellWithReuseIdentifier: cellId)
}
private func setUpDateSource(){
let images: [UIImage] = [UIImage.init(named: "buddha")!, UIImage.init(named: "sharpener")!, UIImage.init(named: "cars")!, UIImage.init(named: "houses")!, UIImage.init(named: "houses2")!, UIImage.init(named: "tower1")!, UIImage.init(named: "tower2")!]
dataSource = images
}
private func setupCollectionViewLayout(){
collectionView.delegate = self
collectionView.dataSource = self
layout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout
layout.minimumInteritemSpacing = interCellSpacing // distance between cells in a row
layout.minimumLineSpacing = spacingBetweenRows // distance in between rows
layout.sectionInset = UIEdgeInsets.init(top: borderInset, left: borderInset, bottom: borderInset, right: borderInset) // border inset for collectionView
}
}
extension GridPicksCollectionViewController: UICollectionViewDelegateFlowLayout{
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return dataSource.count
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! GirdyPickCollectionCell
cell.imageView.image = dataSource[indexPath.row]
return cell
}
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
let selectedImage = dataSource[indexPath.row]
let showImageVC = ImageGridViewController()
showImageVC.modalPresentationStyle = .fullScreen
showImageVC.imageToDisplay = selectedImage
self.present(showImageVC, animated: true) {}
}
// Determine size for UICollectionCell
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
print("sizeForItemAt")
guard let collectionWidth = collectionViewWidth else{ return CGSize.init()}
let widthCell = (collectionWidth - interCellSpacing * 2 - borderInset * 2) / numCelPerRow
return CGSize.init(width: widthCell, height: widthCell)
}
}
You are wrong about your lifecycle of events. When the device is rotated, your view hierarchy becomes notified of this event, and views start to re-layout themselves based on the information they have. After this has been finished, viewDidLayoutSubviews() will be called, not before.
Since you are updating the collectionViewWidth property in this method, the layout still uses the old value when calling collectionView(_:layout:sizeForItemAt:). You need to set this value in viewWillLayoutSubviews().
Alternatively, you can write a setter for this property which will call invalidateLayout() on the collection view's layout, but this will cause an unnecessary layout pass.
I am trying to save a core data string via the first class, then load that string into a collectionviewcell textlabel. I am doing all of this without the use of any storyboards. I am not getting any compile errors. It is just when I load this class, nothing is appearing.
This is a link to my git profile https://github.com/redrock34/collectionViewCellLoad.
class ViewController: UIViewController {
var itemsName: [Item] = []
weak var collectionView: UICollectionView!
override func loadView() {
super.loadView()
let collectionView = UICollectionView(frame: .zero, collectionViewLayout: UICollectionViewFlowLayout())
collectionView.translatesAutoresizingMaskIntoConstraints = false
self.view.addSubview(collectionView)
NSLayoutConstraint.activate([
self.view.topAnchor.constraint(equalTo: collectionView.topAnchor),
self.view.bottomAnchor.constraint(equalTo: collectionView.bottomAnchor),
self.view.leadingAnchor.constraint(equalTo: collectionView.leadingAnchor),
self.view.trailingAnchor.constraint(equalTo: collectionView.trailingAnchor),
])
self.collectionView = collectionView
}
override func viewDidLoad() {
super.viewDidLoad()
self.collectionView.dataSource = self
self.collectionView.delegate = self
self.collectionView.register(Cell.self, forCellWithReuseIdentifier: Cell.identifier)
self.collectionView.alwaysBounceVertical = true
self.collectionView.backgroundColor = .brown
collectionView.reloadData()
}
}
extension ViewController: UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView,
numberOfItemsInSection section: Int) -> Int {
return self.itemsName.count
}
func collectionView(_ collectionView: UICollectionView,
cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: Cell.identifier, for: indexPath) as! Cell
let user = itemsName[indexPath.row]
cell.textLabel?.text = ("\nCourse: \(user.atBATS!) Score: ")
cell.backgroundColor = UIColor.blue
cell.textLabel.textColor = UIColor.black
return cell
}
}
You have an empty dataSource
var itemsName: [Item] = []