I create 1 demo Project like Gaana Application and for that i have added UICollectionView inside multiple UITableViewCell and it works fine but when i scroll UITableView, UITableView not scrolling smoothly.
can you guys please help me to fix this. below is my code.
override func viewDidLoad() {
super.viewDidLoad()
self.tblVW.tableFooterView = UIView(frame: CGRect.zero)
self.tblVW.separatorColor = UIColor.clear
let trendingNib = UINib(nibName: "TrendingCell", bundle: nil)
self.tblVW.register(trendingNib, forCellReuseIdentifier: "TrendingCell")
let topChartNib = UINib(nibName: "TopChartCell", bundle: nil)
self.tblVW.register(topChartNib, forCellReuseIdentifier: "TopChartCell")
let madeForYouNib = UINib(nibName: "MadeForYouCell", bundle: nil)
self.tblVW.register(madeForYouNib, forCellReuseIdentifier: "MadeForYouCell")
let newReleaseNib = UINib(nibName: "NewReleaseCell", bundle: nil)
self.tblVW.register(newReleaseNib, forCellReuseIdentifier: "NewReleaseCell")
let featuredArtistNib = UINib(nibName: "FeaturedArtistCell", bundle: nil)
self.tblVW.register(featuredArtistNib, forCellReuseIdentifier: "FeaturedArtistCell")
let discoverNib = UINib(nibName: "DiscoverCell", bundle: nil)
self.tblVW.register(discoverNib, forCellReuseIdentifier: "DiscoverCell")
let editorsPickNib = UINib(nibName: "EditorsPickCell", bundle: nil)
self.tblVW.register(editorsPickNib, forCellReuseIdentifier: "EditorsPickCell")
let gaanaSpecialNib = UINib(nibName: "GaanaSpecialCell", bundle: nil)
self.tblVW.register(gaanaSpecialNib, forCellReuseIdentifier: "GaanaSpecialCell")
}
func numberOfSections(in tableView: UITableView) -> Int {
return 8
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 1
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
if indexPath.section == 0 {
let cell:TrendingCell = self.tblVW.dequeueReusableCell(withIdentifier: "TrendingCell", for: indexPath) as! TrendingCell
cell.selectionStyle = UITableViewCellSelectionStyle.none
cell.layoutSubviews()
return cell
}
else if indexPath.section == 1 {
let cell:TopChartCell = self.tblVW.dequeueReusableCell(withIdentifier: "TopChartCell", for: indexPath) as! TopChartCell
cell.selectionStyle = UITableViewCellSelectionStyle.none
cell.layoutSubviews()
return cell
}
else if indexPath.section == 2 {
let cell:MadeForYouCell = self.tblVW.dequeueReusableCell(withIdentifier: "MadeForYouCell", for: indexPath) as! MadeForYouCell
cell.selectionStyle = UITableViewCellSelectionStyle.none
cell.layoutSubviews()
return cell
}
else if indexPath.section == 3 {
let cell:NewReleaseCell = self.tblVW.dequeueReusableCell(withIdentifier: "NewReleaseCell", for: indexPath) as! NewReleaseCell
cell.selectionStyle = UITableViewCellSelectionStyle.none
cell.layoutSubviews()
return cell
}
else if indexPath.section == 4 {
let cell:FeaturedArtistCell = self.tblVW.dequeueReusableCell(withIdentifier: "FeaturedArtistCell", for: indexPath) as! FeaturedArtistCell
cell.selectionStyle = UITableViewCellSelectionStyle.none
cell.layoutSubviews()
return cell
}
else if indexPath.section == 5 {
let cell:DiscoverCell = self.tblVW.dequeueReusableCell(withIdentifier: "DiscoverCell", for: indexPath) as! DiscoverCell
cell.selectionStyle = UITableViewCellSelectionStyle.none
cell.layoutSubviews()
return cell
}
else if indexPath.section == 6 {
let cell:EditorsPickCell = self.tblVW.dequeueReusableCell(withIdentifier: "EditorsPickCell", for: indexPath) as! EditorsPickCell
cell.selectionStyle = UITableViewCellSelectionStyle.none
cell.layoutSubviews()
return cell
}
else {
let cell:GaanaSpecialCell = self.tblVW.dequeueReusableCell(withIdentifier: "GaanaSpecialCell", for: indexPath) as! GaanaSpecialCell
cell.selectionStyle = UITableViewCellSelectionStyle.none
cell.layoutSubviews()
return cell
}
}
Below code is once of UITableViewCell code.
class TrendingCell: UITableViewCell {
#IBOutlet weak var trendingCollectionVW: UICollectionView!
var arrData = [String]()
override func awakeFromNib() {
super.awakeFromNib()
trendingCollectionVW.dataSource = self
trendingCollectionVW.delegate = self
let trendingSongsNib = UINib(nibName: "TrendingSongCollectionCell", bundle: nil)
trendingCollectionVW.register(trendingSongsNib, forCellWithReuseIdentifier: "TrendingSongCollectionCell")
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
// override func layoutSubviews() {
// super.layoutSubviews()
//
// self.layer.shouldRasterize = true
// self.layer.rasterizationScale = UIScreen.main.scale
// }
}
//MARK: - UICollectionView Delegate & DataSource
extension TrendingCell: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 10
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "TrendingSongCollectionCell", for: indexPath) as! TrendingSongCollectionCell
cell.lblTItle.text = String.init(format: "Indexpath %d", indexPath.item)
cell.imgVW.image = UIImage.init(named: String.init(format: "trendingSong%d", indexPath.item+1))
//cell.layoutSubviews()
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: (UIScreen.main.bounds.size.width - 15) / 2.9, height: 175)
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
print("You selected cell #\(indexPath.item)!")
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
return UIEdgeInsetsMake(0, 5, 5, 5)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 5
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 5
}
}
When i scroll any of UICollectionView inside UITableViewCell, Suddenly 15 to 20 MB memory increased.
Edit
Here is demo Project Link : https://www.dropbox.com/s/k1vpdqn9moli9nw/Gaana.zip?dl=0
Any help will be appreciated.
Thanks
Here are several things you are doing wrong.
Problems:
Creating the nib every time
let trendingSongsNib = UINib(nibName: "TrendingSongCollectionCell", bundle: nil)
Registerring the nib in the wrong place
cell.trendingCollectionVW.register(trendingSongsNib, forCellWithReuseIdentifier: "TrendingSongCollectionCell")
Even after registering you try to dequeue using different reusing identifier
let cell:TrendingCell = self.tblVW.dequeueReusableCell(withIdentifier: "TrendingCell", for: indexPath) as! TrendingCell
Even if you successfully dequeue a cell, you create the nib again and again in each call
let trendingSongsNib = UINib(nibName: "TrendingSongCollectionCell", bundle: nil)
As each time collection view get created, it loads the data
// whole architecture is responsible for this, no particular code.
Solution
You can register the cell's #viewDidLoad or in the interface builder
Do not dynamically load nib, dequeue will automatically do it.
you are creating nibs every time which is already reusable and calling layoutSubviews() in cellfor method will create this issue
you can do following changes to your code
let trendingSongsNib = UINib(nibName: "TrendingSongCollectionCell", bundle: nil)
cell.trendingCollectionVW.register(trendingSongsNib, forCellWithReuseIdentifier: "TrendingSongCollectionCell")
put this lines in your cell's awakeFromNib()
so it will register cell at the time of creating your tableviewcell
and stop calling cell.layoutSubviews()
Related
Good afternoon,
I am trying to create expandable/ collapsible cells in a UICollectionViewController. The cells expand and collapse correctly. However, the information each cell holds stays present on the screen in the background. I will show pictures to explain. I am trying to delete the information from the view if the user collapses the cell, and insert it back if the user expands that cell.
The images below express the process of the cell starting in a collapsed state, expanding that cell, them collapsing that cell again. (note: this happens to every cell not just the first cell I clicked.
the first image is when the view loads and the cells are in the original collapsed state.
this second image shows when the user taps on the cell to expand it.
the third image shows when the user tries to collapse the cell.
the code that I use to expand and collapse the cells are below
fileprivate let cellId = "cellId"
fileprivate let headerId = "headerId"
fileprivate let profID = "profID"
private let headerIdentifier = "userProfileHeader"
private let sectionIdentifier = "sectionHeader"
var section:Int?
var expandSection = [Bool]()
var items = [String]()
fileprivate func setupCollectionView() {
collectionView.backgroundColor = .white
collectionView.contentInsetAdjustmentBehavior = .never
collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: cellId)
self.expandSection = [Bool](repeating: false, count: self.items.count)
collectionView.dataSource = self
collectionView.delegate = self
collectionView.register(userProfileHeader.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: headerIdentifier)
collectionView.register(sectionHeader.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: sectionIdentifier)
}
fileprivate func registerCollectionView() {
collectionView.register(profCell.self, forCellWithReuseIdentifier: "profCell")
self.collectionView.register(userProfileHeader.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: headerIdentifier)
self.collectionView.register(sectionHeader.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: sectionIdentifier)
}
var headerView: userProfileHeader?
var sectionView: sectionHeader?
override func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
if kind == UICollectionView.elementKindSectionHeader {
let headerView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: headerIdentifier, for: indexPath) as? userProfileHeader
if let user = self.user {
headerView?.myUser = user
} else if let userToLoad = self.userToLoad {
headerView?.myUser = userToLoad
}
return headerView!
} else {
let sectionViews = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: sectionIdentifier, for: indexPath) as? sectionHeader
let categories = ["Skills, Preferences", "Bio", "Reviews"]
sectionViews!.headerLabel.text = categories[indexPath.section]
sectionViews!.backgroundColor = .lightGray
return sectionViews!
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return .init(width: view.frame.width, height: 340)
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return items.count
}
override func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
self.expandSection[indexPath.row] = !self.expandSection[indexPath.row]
self.collectionView.reloadItems(at: collectionView.indexPathsForSelectedItems!)
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "profCell", for: indexPath) as! profCell
if indexPath.row == 0 {
cell.educationView.text = user.education
cell.skillsView.text = user.skills
cell.preferencesView.text = "wassup bitches"
} else if indexPath.row == 1 {
cell.bioLabel.text = user.bio
} else if indexPath.row == 2 {
cell.labels.text = "Reviews"
}
}
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
if self.expandSection[indexPath.row] {
return CGSize(width: self.view.bounds.width - 20, height: 300)
}else{
return CGSize(width: self.view.bounds.width - 20, height: 80)
}
}
Instead of trying to insert and remove items inside sizeForItemAt(), call reloadSections(_ sections: IndexSet) for the sections that get expanded or contracted. Then implement numberOfItems(inSection section: Int) to return 0 when contracted or items.count when expanded. Use sections to hold the top level items and cells to hold the collapsible sub-items.
I have a collection view which is nested inside of a table view cell. The first cell in the collection view is a button which allows users to create a new list. Its width is smaller than that of the main lists cells. I recently changed the code around so that the collectionView delegate and dataSource methods are in the tableViewController instead of the table view cell, however now the first cells width is not changing as it did before moving the code. This picture shows:
If I press into the blank space it is registering that I clicked the plus cell.
The code for all the collectionView delegate and dataSource methods:
extension ProfileTableViewController: UICollectionViewDelegate, UICollectionViewDataSource {
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
print("the media: \(usersLists.count)")
return usersLists.count + 1
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if indexPath.item == 0 {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "addNewListCell", for: indexPath) as! addNewListCell
cell.currentUser = currentUser
return cell
}else{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "listCell", for: indexPath) as! userListsCell
cell.layer.applySketchShadow()
cell.layer.cornerRadius = 20
cell.layer.masksToBounds = false
cell.currentUser = currentUser
cell.media = usersLists[indexPath.item-1]
return cell
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize{
if indexPath.item == 0 {
let size = CGSize(width: 80, height: 158)
return size
}else{
let size = CGSize(width: 158, height: 158)
return size
}
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
if indexPath.item == 0 {
//button
self.addListDelegate?.addNewItem()
}
}
I tested if changing any values in the size in sizeForItemAt would change the cell size and nothing changes in any cells
the table view methods which are in the ProfileTableViewController class and not the extension:
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "profileCell", for: indexPath) as! profileCell
cell.selectionStyle = .none
return cell
}
override func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
guard let tableViewCell = cell as? profileCell else { return }
tableViewCell.setCollectionViewDataSourceDelegate(dataSourceDelegate: self, forRow: indexPath.row) //this line sets the collectionView delegate and datasouce so that I can have all of the collectionView methods in this class
}
and this is the code inside of the tableViewCell
protocol addListCollectionDelegate: class {
func addNewItem()
}
class profileCell: UITableViewCell, UICollectionViewDelegate {
#IBOutlet weak var collectionView: UICollectionView!
override func awakeFromNib() {
super.awakeFromNib()
collectionView.register(UINib(nibName: "usersLists", bundle: nil), forCellWithReuseIdentifier: "listCell")
collectionView.register(UINib(nibName: "newListCell", bundle: nil), forCellWithReuseIdentifier: "addNewListCell")
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
func setCollectionViewDataSourceDelegate
<D: UICollectionViewDataSource & UICollectionViewDelegate>
(dataSourceDelegate: D, forRow row: Int) {
collectionView.delegate = dataSourceDelegate
collectionView.dataSource = dataSourceDelegate
collectionView.reloadData()
}
}
Does anyone know how to change the width of the first cell since sizeForItemAt is not changing the size? Thanks
You forgot to add this protocol: UICollectionViewDelegateFlowLayout
It is required when you want to return custom size for an item.
Also improve your code like below:
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if indexPath.item == 0 {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "addNewListCell", for: indexPath) as! addNewListCell
cell.currentUser = currentUser
return cell
}
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "listCell", for: indexPath) as! userListsCell
cell.layer.applySketchShadow() // Write this line in cell class
cell.layer.cornerRadius = 20 // Write this line in cell class
cell.layer.masksToBounds = false // Write this line in cell class
cell.currentUser = currentUser
cell.media = usersLists[indexPath.item - 1]
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize{
return indexPath.item == 0 ? CGSize(width: 80, height: 158) : CGSize(width: 158, height: 158)
}
Try to use UICollectionViewDelegateFlowLayout method. In Xcode 11 or later, you need to set Estimate Size to none from Xib.
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout:
UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let padding: CGFloat = 170
let collectionViewSize = advertCollectionView.frame.size.width - padding
return CGSize(width: collectionViewSize/2, height: collectionViewSize/2)
}
I am trying to have two collection views on one view controller. There are many posts guiding people through this but I cannot tell what I am doing wrong.
My code is the following,
class FeedVC: UIViewController {
#IBOutlet var collectionView: UICollectionView!
#IBOutlet var collectionViewProgress: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
collectionView.dataSource = self
collectionView.delegate = self
collectionViewProgress.dataSource = self
collectionViewProgress.delegate = self
}
}
extension FeedVC: UICollectionViewDelegate, UICollectionViewDataSource{
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if (collectionView == self.collectionView){
return 10
}else{
return 1
}
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
print("hre")
if (collectionView == self.collectionView){
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "UnclaimedCVC", for: indexPath) as? UnclaimedCVC {
cell.configureCell()
return cell
}else{
return UICollectionViewCell()
}
}else if(collectionView == self.collectionViewProgress){
if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "InProgressCVC", for: indexPath) as? InProgressCVC {
cell.configureCell()
return cell
}else{
return UICollectionViewCell()
}
}else{
return UICollectionViewCell()
}
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
if (collectionView == self.collectionView){
return 1
}else{
return 1
}
}
}
I am currently getting the error,
'could not dequeue a view of kind: UICollectionElementKindCell with
identifier InProgressCVC - must register a nib or a class for the
identifier or connect a prototype cell in a storyboard'
In viewDidLoad put
collectionView.register(UnclaimedCVC.self, forCellWithReuseIdentifier: "UnclaimedCVC ")
collectionViewProgress.register(InProgressCVC.self, forCellWithReuseIdentifier: "InProgressCVC ")
If you created them as Xibs
collectionView.register(UINib.init(nibName: "UnclaimedCVC", bundle: nil), forCellWithReuseIdentifier: "UnclaimedCVC")
collectionViewProgress.register(UINib.init(nibName: "InProgressCVC", bundle: nil), forCellWithReuseIdentifier: "InProgressCVC")
I have a horizontally scrollable UICollectionView with three cells each of which are different subclasses of UICollectionViewCell. Each one of these cells contains a UITableView.
Inside of the first two cells, my table view cells are the same subclasses of UITableViewCell and have just a UIImageView. I use it to set its backgroundColor. Inside of the third cell, my table view's cells are different subclasses of UITableViewCell than in the previous two. They have both a UILabel and a UIImageView. The label has some dummy text, and I set imageView's backgroundColor to some color, again.
In order to follow MVC pattern, I use my UIViewController as a data source and a delegate for both collection view, and table view. Here is the code of UIViewController:
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
let collectionViewCellId = "collectionViewCell"
let tableViewCellId = "tableViewCell"
let collectionViewCellId2 = "collectionViewCellId2"
let collectionViewCellId3 = "collectionViewCellId3"
let tableViewCellDif = "tableViewCellDif"
var collectionViewIndex: Int?
#IBOutlet weak var collectionView: UICollectionView! {
didSet {
collectionView.delegate = self
collectionView.dataSource = self
collectionView.isPagingEnabled = true
}
}
//MARK: UITableViewDataSource
public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return 5
}
public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let colors: [UIColor] = [.red, .green, .purple, .orange, .blue]
let colors2: [UIColor] = [.blue, .brown, .yellow, .magenta, .cyan]
if collectionViewIndex == 0 {
let cell = tableView.dequeueReusableCell(withIdentifier: tableViewCellId, for: indexPath) as! TableViewCell
cell.colorForImageView = colors[indexPath.row]
return cell
} else
if collectionViewIndex == 1 {
let cell = tableView.dequeueReusableCell(withIdentifier: tableViewCellId, for: indexPath) as! TableViewCell
cell.colorForImageView = colors2[indexPath.row]
return cell
} else
if collectionViewIndex == 2 {
let cell = tableView.dequeueReusableCell(withIdentifier: tableViewCellDif, for: indexPath) as! TableViewCellDifferent
cell.colorForImageView = colors2[indexPath.row]
return cell
} else {
return UITableViewCell()
}
}
}
//MARK: UICollectionViewDataSource
extension ViewController: UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 3
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let identifier: String
if indexPath.item == 0 {
identifier = collectionViewCellId
} else if indexPath.item == 1 {
identifier = collectionViewCellId2
} else if indexPath.item == 2 {
identifier = collectionViewCellId3
} else {
identifier = ""
}
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: identifier, for: indexPath)
return cell
}
}
//MARK: UICollectionViewDelegate
extension ViewController: UICollectionViewDelegate {
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
if indexPath.item == 0 {
let cell = cell as! CollectionViewCell
cell.tableView.dataSource = self
cell.tableView.delegate = self
collectionViewIndex = 0
}
if indexPath.item == 1 {
let cell = cell as! CollectionViewCell2
cell.tableView.dataSource = self
cell.tableView.delegate = self
collectionViewIndex = 1
}
if indexPath.item == 2 {
let cell = cell as! CollectionViewCell3
cell.tableView.dataSource = self
cell.tableView.delegate = self
collectionViewIndex = 2
print (collectionViewIndex)
}
}
}
//MARK: UICollectionViewDelegateFlowLayout
extension ViewController: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let layout = collectionViewLayout as! UICollectionViewFlowLayout
layout.minimumInteritemSpacing = 0
layout.minimumLineSpacing = 0
return CGSize(width: collectionView.frame.width, height: collectionView.frame.height)
}
}
As I stated in a title of the question, nothing happens on a background thread. I, basically, only set the backgroundColor of table view's cells.
The problem is that inside the collection view's third cell (and only inside of there), my table view dequeues its cells only after a minor scroll or tap happens. Here is how it looks like:
I can't figure out why this happens. Maybe, this happens because inside of the third cell of the collection view, my table view's cells are instances of different subclass than inside of the first two?
EDITED
I could solve the problem by reloading the table view before before showing the collection view's each cell but I'm not sure that this is the most efficient solution. Here is the code:
//MARK: UICollectionViewDelegate
extension ViewController: UICollectionViewDelegate {
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
if indexPath.item == 0 {
let cell = cell as! CollectionViewCell
cell.tableView.dataSource = self
cell.tableView.delegate = self
cell.tableView.reloadData()
collectionViewIndex = 0
}
if indexPath.item == 1 {
let cell = cell as! CollectionViewCell2
cell.tableView.dataSource = self
cell.tableView.delegate = self
cell.tableView.reloadData()
collectionViewIndex = 1
}
if indexPath.item == 2 {
let cell = cell as! CollectionViewCell3
cell.tableView.dataSource = self
cell.tableView.delegate = self
cell.tableView.reloadData()
collectionViewIndex = 2
}
}
}
If you know a better way, I would appreciate your help.
I gave this a try, and saw the same results. So, I moved your collection view cell "setup" code from willDisplay cell: to cellForItemAt and it fixed the problem.
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if indexPath.item == 0 {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: collectionViewCellId, for: indexPath) as! CollectionViewCell
cell.tableView.dataSource = self
cell.tableView.delegate = self
collectionViewIndex = 0
return cell
}
if indexPath.item == 1 {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: collectionViewCellId2, for: indexPath) as! CollectionViewCell2
cell.tableView.dataSource = self
cell.tableView.delegate = self
collectionViewIndex = 1
return cell
}
// if we get here, indexPath.item must equal 2
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: collectionViewCellId3, for: indexPath) as! CollectionViewCell3
cell.tableView.dataSource = self
cell.tableView.delegate = self
collectionViewIndex = 2
return cell
}
Now, since you're not showing your code for your tableview cells, it's possible there might be another issue, but this worked for me:
class TableViewCell: UITableViewCell {
#IBOutlet var theImageView: UIImageView!
var colorForImageView: UIColor = UIColor.gray {
didSet {
self.theImageView.backgroundColor = colorForImageView
}
}
}
You can try to dequeue CollectionViewCell or TableViewCell explicitly on the main thread
DispatchQueue.main.async {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: identifier, for: indexPath)
}
or
DispatchQueue.main.async {
let cell = tableView.dequeueReusableCell(withIdentifier: tableViewCellDif, for: indexPath) as! TableViewCellDifferent
cell.colorForImageView = colors2[indexPath.row]
}
It could help to wake up the main thread
But in general, it would be much easier if a data source for the table view was inside collection view cell
I have two different cell type classes and i'm trying to make the first indexpath with the class PayNowCell, have it remain displayed. While the other cells are of class CheckOutCell. Now the problem is in my func numberofitemsinsection. Currently i'm using return checkout.count but it missing the PayNowCell when view loads. If i make it return checkout.count+1 to always have the PayNowCell available; my program crashes giving me the error index out of bounds. The array checkout is a global var. Can someone explain why and provide a fix? Been stuck on this for a while. Code Below.
class CheckoutController: UICollectionViewCell, UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {
var inventoryTabController: InventoryTabController?
override init(frame: CGRect){
super.init(frame: frame)
setupViews()
NotificationCenter.default.addObserver(forName: .arrayValueChanged, object: nil, queue: OperationQueue.main) { [weak self] (notif) in
self?.collectionView.reloadData()
}
}
deinit {
NotificationCenter.default.removeObserver(self)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func loadItems() -> [Item]? {
return NSKeyedUnarchiver.unarchiveObject(withFile: Item.ArchiveURL.path) as? [Item]
}
func saveItems() {
let isSuccessfulSave = NSKeyedArchiver.archiveRootObject(checkout, toFile: Item.ArchiveURL.path)
if !isSuccessfulSave {
print("Failed to save items...")
}
}
func addItem(item: Item) {
items.append(item)
collectionView.reloadData()
}
func editItem(item: Item, index: Int) {
items[index] = item
collectionView.reloadData()
}
func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// Identify which segue is occuring.
if segue.identifier == "ShowDetail" {
let itemDetailViewController = segue.destination as! AddItemController
// Get the cell that generated this segue.
if let selectedItemCell = sender as? InventoryCell {
let indexPath = collectionView.indexPath(for: selectedItemCell)!
let selectedItem = items[indexPath.row]
itemDetailViewController.item = selectedItem
}
}
else if segue.identifier == "AddItem" {
print("Adding new meal.")
}
}
lazy var collectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
cv.dataSource = self
cv.delegate = self
cv.backgroundColor = UIColor.rgb(r: 247, g: 247, b: 247)
return cv
}()
let cellId = "cellId"
let paynow = "paynow"
func setupViews() {
backgroundColor = .brown
addSubview(collectionView)
addConstraintsWithFormat("H:|[v0]|", views: collectionView)
addConstraintsWithFormat("V:|[v0]|", views: collectionView)
collectionView.indicatorStyle = UIScrollViewIndicatorStyle.white
collectionView.register(PayNowCell.self, forCellWithReuseIdentifier: paynow)
collectionView.register(CheckoutCell.self, forCellWithReuseIdentifier: cellId)
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return checkout.count //init number of cells
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if indexPath.item == 0 {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "paynow", for: indexPath) as! PayNowCell //init cells
return cell
}else{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellId", for: indexPath) as! CheckoutCell //init cells
print("Printing this \(checkout.count)")
cell.item = checkout[indexPath.item]
return cell
}
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
//let item = items[indexPath.item]
//inventoryController?.showItemDetailForItem(item: item, index: indexPath.item)
print("selected")
print(indexPath.item)
collectionView.reloadData()
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
if indexPath.item == 0 {
return CGSize(width:frame.width, height: 100) //each cell dimensions
}else{
return CGSize(width:frame.width, height: 150) //each cell dimensions
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
It's better to re-arrange your collection view to have 2 sections:
Section 0: PayNow cell (only 1 cell)
Section 1: Checkout cells (using checkout array list)
Then you don't have any confusion about the indexPath.item issue.
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 2
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return section == 0 ? 1 : checkout.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if indexPath.section == 0 {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "paynow", for: indexPath) as! PayNowCell //init cells
return cell
} else {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellId", for: indexPath) as! CheckoutCell //init cells
print("Printing this \(checkout.count)")
cell.item = checkout[indexPath.item]
return cell
}
}
You need to subtract 1 from your cellForRow function. Since you are adding the PayNowCell you are adding one extra indexPath, but currently, you are using the default indexPath given by the dataSource function. That index will always be one higher than the count of your items. By subtracting 1 from the indexPath, you will be back in sync with your itemsArray, taking into account the PayNowCell.
cell.item = checkout[indexPath.item - 1]