I am developing appleTV application.
I have a UICollectionView inside a UICollectionView cell.
When the data is updated, the CollectionView placed in the ViewController is reloadData, and at the same time, the CollectionView in the CollectionView is also reloadData.
Then focus does not return to the original position in CollectionView.
The CollectionView placed in the ViewController is canFocusItemAt false.
What should I do?
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if collectionView === self.collectionView {
return 10
} else {
return 10
}
}
func collectionView(_ collectionView: UICollectionView, canFocusItemAt indexPath: IndexPath) -> Bool {
if collectionView === self.collectionView {
return false
} else {
return true
}
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if collectionView === self.collectionView {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "aaaa", for: indexPath)
if let collectionView = cell.viewWithTag(20) as? UICollectionView {
collectionView.delegate = self
collectionView.dataSource = self
collectionView.reloadData()
}
return cell
} else {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "bbbb", for: indexPath)
return cell
}
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
self.collectionView.reloadData()
}
Related
I have a collectionViewCell which contains an image and a label. When I select a cell and scroll ahead I find other cell being selected. Also when I scroll back I find the other cell and not the cell I selected is selected.
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return followedUsers.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = attachProfilesCollectionView.dequeueReusableCell(withReuseIdentifier: "attachCells", for: indexPath) as? attachUsersCell
cell!.subscribedUserId = self.followedUsers[indexPath.row].userId
cell?.profileNameToAttah.text = self.followedUsers[indexPath.row].fullName
cell?.profileImageToAttch.loadImagesWithUrl(from: self.followedUsers[indexPath.row].ImagePath)
if mLastSelectedIndex == indexPath.row {
cell?.isSelected = true}
else{cell?.isSelected = false}
return cell!
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 80, height: 110)
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
let cell = attachProfilesCollectionView.cellForItem(at: indexPath) as! attachUsersCell
cell.subscribedUserId = following[indexPath.item]
usersToAttach.append(cell.subscribedUserId)
attachedCounter += 1
attachCounterFun()
print(usersToAttach)
cell.checkMarkImage.isHidden = false
attachCounterFun()
guard mLastSelectedIndex != indexPath.row else{return}
mLastSelectedIndex = indexPath.row
print("this is addition \(usersToAttach)")
}
func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
let cell_ = attachProfilesCollectionView.cellForItem(at: indexPath) as! attachUsersCell
let toRemove = usersToAttach.index(of: following[indexPath.row])
usersToAttach.remove(at: toRemove!)
attachedCounter -= 1
attachCounterFun()
print(usersToAttach)
cell_.checkMarkImage.isHidden = true
print("this is removal \(usersToAttach)")
}
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
if isSelected {
cell.isSelected = true}
else { isSelected = false }
}
At present I have enabled paging and almost there but occasionally the selected cells change selection upon scroll
Maintain global variable in your controller
var mLastSelectedIndex = -1
Whenever cellForRowAtIndexPath method called check if current cell is selected or not .If this is selected One update its UI. I suggest you to change selected cell UI on cell class only. This way you can easily manage cell tapping and helps you writing clean code.
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = attachProfilesCollectionView.dequeueReusableCell(withReuseIdentifier: "attachCells", for: indexPath) as? attachUsersCell
cell!.subscribedUserId = self.followedUsers[indexPath.row].userId
cell?.profileNameToAttah.text = self.followedUsers[indexPath.row].fullName
cell?.profileImageToAttch.loadImagesWithUrl(from: self.followedUsers[indexPath.row].ImagePath)
// here update selected index path
if mLastSelectedIndex == indexPath.row {
cell?.isSelected = true
}
else{
cell?.isSelected = false
}
return cell!
}
Update last selected index on cell tapped.
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
guard mLastSelectedIndex != IndexPath.row else{return}
let indexpath = IndexPath(row:mLastSelectedIndex, section: 0)
mColllectionView.cellForItem(at: indexpath)?.isSelected = !mColllectionView.cellForItem(at: indexpath)!.isSelected
mLastSelectedIndex = IndexPath.row
}
In your attachUsersCell.swift declare isSelected property of cell . The default value of this property is false, which indicates that the cell is not selected.
override var isSelected: Bool{
didSet{
if isSelected {
setSelectedUI()
}
else{
setUnSelectedUI()
}
}
}
func setSelectedUI(){
borderColor = UIColor.systemOrange
borderWidth = 2
cornerRadius = 8
clipsToBounds = true
}
func setUnSelectedUI(){
// reset to default ui
}
Hope this helps!
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 using Swift4 and Xcode9.
I create my collectionView cells by using the delegate method below;
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "mediaItemCell", for: indexPath) as! MediaItemCollectionViewCell
cell.mediaItemCellImageView.image = mediaPlayer?.item(at: indexPath.row)?.image
return cell
}
Then, I want to replace the image of selected cell with a "stop" image. To achieve this, I have tried to use didSelectItemAt method;
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
if (mediaPlayer?.isPlaying == true) {
// stop the player
mediaPlayer?.stopPlayingMedia()
} else {
// change the image and start playing
let cell = collectionView.cellForItem(at: indexPath) as! MediaItemCollectionViewCell // CRASH
cell.mediaItemCellImageView.image = UIImage(named: "stop.png")
...
...
}
}
func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
// restore the original image
let cell = collectionView.cellForItem(at: indexPath) as! MediaItemCollectionViewCell
cell.mediaItemCellImageView.image = mediaPlayer?.item(at: indexPath.row)?.image
// stop playing
mediaPlayer?.stopPlayingMedia()
}
Now, when I select the cell which is already selected (hence the original image has already been replaced with "stop.png") the code above works; i.e. the original image is restored, which is done by stopPlayingMedia() method.
When I select a cell different than the currently selected one, the App crashes. I tried to move the didSelectItemAt call out of the delegate method, but it did not work.
Surprisingly, the logical check if collectionView.cellForItem(at: indexPath) is MediaItemCollectionViewCell succeeds when I select the currently selected cell, and fails when I select another cell.
I want to change the image of the cell, hence need to cast the variable type but it fails. Why does to cast fail when I select a different cell than the currently selected one?
Thanks
Edit:
I use collectionView.reloadData() to restore all the images to originals (I mentioned this in the OP - when stopPlayingMedia() is invoked). It appears that, if I add a private var index:IndexItem? to my ViewController class and update its value within didSelectItemAt (to save the last selected cell) and use the code below, the code does not crash
extension ViewController:MediaPlayerControllerDelegate {
// this delegate method is invoked when stopPlayingMedia() is called
func mediaPlayerControllerDidFinishPlaying() {
// restore the UI
// collectionView.reloadData() -> this causes the crash, instead, I only restore one cell
let cell = collectionView.cellForItem(at: index!) as! MediaItemCollectionViewCell
cell.mediaItemCellImageView.image = mediaPlayer?.item(at: (index?.row)!)?.image
timeLabel.text = "00:00"
progressBar.progress = 0.0
}
}
I tried the following to create cell and changing the image inside cell on selection. Not crashing at all. Please check the implementation, It might help you.
import UIKit
class ViewController: UIViewController {
private var isPlayingModel = [false, false, false, false, false] // initially all are stop, not playing
#IBOutlet weak var collectionView: UICollectionView! {
didSet{
collectionView.delegate = self
collectionView.dataSource = self
}
}
}
extension ViewController: UICollectionViewDataSource {
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return isPlayingModel.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "mediaItemCell", for: indexPath) as! MediaItemCollectionViewCell
cell.imageVw.image = isPlayingModel[indexPath.row] ? #imageLiteral(resourceName: "start") : #imageLiteral(resourceName: "stop")
return cell
}
}
extension ViewController: UICollectionViewDelegate {
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
isPlayingModel[indexPath.row] = !isPlayingModel[indexPath.row]
let cell = collectionView.cellForItem(at: indexPath) as! MediaItemCollectionViewCell
cell.imageVw.image = isPlayingModel[indexPath.row] ? #imageLiteral(resourceName: "start") : #imageLiteral(resourceName: "stop")
}
}
extension ViewController: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: view.frame.size.width, height: 60)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 4
}
}
class MediaItemCollectionViewCell: UICollectionViewCell {
#IBOutlet weak var imageVw: UIImageView!
}
Check the implementation here.
You are not passing indexPath correctly to load a cell, that's why it is crashing.Edit your didSelectItemAt: method as follows:
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
let selectedCell = IndexPath(item: indexPath.item, section: indexPath.section)
let cell = collectionView.cellForItem(at: selectedCell) as! ACollectionViewCell
cell.imgView.image = UIImage(named: "3.jpg")
}
Collection view indexPath has element item, and not row
Try this and see: (let me know what does it print)
func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
// restore the original image
if let cell = collectionView.cellForItem(at: indexPath) as? MediaItemCollectionViewCell {
if let cellImage = mediaPlayer?.item(at: indexPath.item)?.image { // Collection view indexPath has element `item`, and not `row`
cell.mediaItemCellImageView.image = cellImage
} else {
print("cellImage not found at indexPath - \(indexPath)")
}
} else {
print("collection view cell `MediaItemCollectionViewCell` not found at indexPath -\(indexPath) ")
}
// stop playing
mediaPlayer?.stopPlayingMedia()
}
I'm trying to use prefetching which was introduced in iOS 10. But unable to achieve it.
I do set the delegate and enable the prefetching. But when i set a breakpoint or console log at prefetch, it does not pass through the function ever.
I know on fast scroll, the prefetching is skipped. but even on slowest scroll, its never been called
var dataSource = [IndexPath: Any]()
override func viewDidLoad() {
if #available(iOS 10.0, *) {
mainCollectionView.isPrefetchingEnabled = true
mainCollectionView.prefetchDataSource = self
}
//Other stuffs
}
//This is not being called
func collectionView(_ collectionView: UICollectionView, prefetchItemsAt indexPaths: [IndexPath]) {
print("Prefectch")
for indexPath in indexPaths {
dataSource[indexPath] = fetchDataSource(indexPath)
}
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "MyCell", for: indexPath) as! MyCell
cell.dataSource = dataSource[indexPath] ?? fetchDataSource(indexPath)
return cell
}
Call
override func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
self.collectionView(collectionView, prefetchItemsAt: [indexPath])
}
To trigger the prefetch, and remove:
collectionViewLayout.estimatedItemSize = UICollectionViewFlowLayout.automaticSize
If you have it.
This was by me the case.
I am unable to display the second cell despite registering it to the collectionView. Does anyone know why this is the case? The cell exists as when I switch the row the other cell displays instead.
class ViewController: UICollectionViewController, UICollectionViewDelegateFlowLayout {
override func viewDidLoad() {
super.viewDidLoad()
collectionView?.backgroundColor = UIColor.white
collectionView?.register(HeaderCell.self, forCellWithReuseIdentifier: "HeaderCell")
collectionView?.register(SummaryCell.self, forCellWithReuseIdentifier: "SummaryCell")
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if section == 0 {
return 1
}
return 1
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if (indexPath.row == 0) {
let cell1 = collectionView.dequeueReusableCell(withReuseIdentifier: "HeaderCell", for: indexPath) as! HeaderCell
return cell1
} else {
let cell2 = collectionView.dequeueReusableCell(withReuseIdentifier: "SummaryCell", for: indexPath) as! SummaryCell
return cell2
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: view.frame.width, height: 200)
}
}
I have looked a this but still unable to get it to work.
P.S. I am programming everything programmatically.
You have registered 2 cells but you are returning only 1 row.Try returning 2 items.
//numberOfItemsInSection
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int{
return 2
}
None of the answer correctly/completely solves the issue. However I did use some of the suggestions to get it to work properly by adding the following:
override func numberOfSections(in collectionView: UICollectionView) -> Int {
return 2
}
And changing indexPath.row to indexPath.section
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if (indexPath.section == 0) {
let cell1 = collectionView.dequeueReusableCell(withReuseIdentifier: "HeaderCell", for: indexPath) as! HeaderCell
return cell1
} else {
let cell2 = collectionView.dequeueReusableCell(withReuseIdentifier: "SummaryCell", for: indexPath) as! SummaryCell
return cell2
}
}