My problem is that when I present this CollectionViewController which has 2 cells with a horizontal layout, I'd like to start at index 1 and not index 0.
What am I missing?
class Controller: UICollectionViewController, UICollectionViewDelegateFlowLayout {
let cellId = "cell"
override func viewDidLoad() {
scrollToIndex(index: 1)
setupSwipeView()
}
func setupSwipeView() {
if let flowLayout = collectionView?.collectionViewLayout as? UICollectionViewFlowLayout {
flowLayout.scrollDirection = .horizontal
flowLayout.minimumLineSpacing = 0
}
collectionView?.register(UICollectionViewCell.self, forCellWithReuseIdentifier: cellId)
collectionView?.isPagingEnabled = true
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 2
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: self.cellId, for: indexPath)
return cell
}
func scrollToIndex(index: Int) {
let indexPath = NSIndexPath(item: index, section: 0)
collectionView?.scrollToItem(at: indexPath as IndexPath, at: .right, animated: false)
}
}
No need to do anything in viewWillAppear and viweDidAppear, just try this one in your collection view willDisplay cell delegate method:
Swift 3 and above:
var startWithIndexPath: IndexPath? = .init(item: 1, section: 0)
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
if let startWithIndexPath = startWithIndexPath {
if collectionView.isValidIndexPath(indexpath: startWithIndexPath) {
self.collectionView.scrollToItem(at: startWithIndexPath, at: .left, animated: false)
}
self.startWithIndexPath = nil
}
}
Note: Make sure you are providing valid IndexPath which exist in collection view and cell items should be these already and this logic should execute only once.
Related
How to get the selected cells count and selected cells array from UICollectionView, I need to set the limit of selection. Below is my code which is not working. Please guide. Thanks
func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
let indexPaths = collectionView.indexPathsForSelectedItems!
print(indexPaths)
if let selectedItems = collectionView.indexPathsForSelectedItems {
if selectedItems.count >= 3 {
collectionView.deselectItem(at: indexPath as IndexPath, animated: true)
return false
}
}
return true
}
Above code when written in didSelect method returns only selected cell index but here just skip to last line
return true
You can use the shouldSelectItemAt delegate method from the UICollectionViewDelegate to achieve that:
func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
return collectionView.indexPathsForSelectedItems?.count ?? 0 <= selectionLimit
}
A sample demo to demonstrate how it works:
class ViewController : UIViewController {
private var myCollectionView:UICollectionView?
private var selectionLimit = 4
override func viewDidLoad() {
super.viewDidLoad()
let view = UIView()
view.backgroundColor = .white
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.sectionInset = UIEdgeInsets(top: 20, left: 10, bottom: 10, right: 10)
layout.itemSize = CGSize(width: UIScreen.main.bounds.width * 0.7, height: 60)
myCollectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)
myCollectionView?.register(UICollectionViewCell.self, forCellWithReuseIdentifier: "MyCell")
myCollectionView?.backgroundColor = UIColor.white
myCollectionView?.allowsMultipleSelection = true
myCollectionView?.dataSource = self
myCollectionView?.delegate = self
view.addSubview(myCollectionView ?? UICollectionView())
self.view = view
}
}
extension ViewController: UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 20
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let myCell = collectionView.dequeueReusableCell(withReuseIdentifier: "MyCell", for: indexPath)
myCell.backgroundColor = UIColor.blue
return myCell
}
}
extension ViewController: UICollectionViewDelegate {
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
print("Did select a cell at \(indexPath.row)")
let itemsLeftToSelect = selectionLimit - (collectionView.indexPathsForSelectedItems?.count ?? 0)
print("Have \(itemsLeftToSelect) items to select")
}
func collectionView(_ collectionView: UICollectionView, didDeselectItemAt indexPath: IndexPath) {
print("Did deselect a cell at \(indexPath.row)")
let itemsLeftToSelect = selectionLimit - (collectionView.indexPathsForSelectedItems?.count ?? 0)
print("Have \(itemsLeftToSelect) items to select")
}
func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
return collectionView.indexPathsForSelectedItems?.count ?? 0 < selectionLimit
}
}
When you reach the selection limit, shouldSelectItemAt will return false and didSelectItemAt function will not be called anymore. On the other hand if you click on the already selected cell, didDeselectItemAt will be called and you will be called, and you are able to select + 1 cell again, as the number of selected items will decrease with 1. See also the debug logs in the example.
A better approach is model based.
In your data model add a property
var isSelected = false
and re-/set it accordingly when a cell is de-/selected.
Then you can simply count the selected data source items – dataSource represents the data source array
func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
return dataSource.filter{$0.isSelected}.count < 3
}
Further there is no need to deselect a row in this method as you are preventing the user from selecting more than 2 rows.
App Scheme-
As you can see from my App Scheme I have UITableView and inside UITableViewCells I have UICollectionView.
My question right now is how to get UITableView row when user taps on UICollectionViewCell?
I tried this but that doesn't work me:
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
collectionView.scrollToItem(at: indexPath, at: .centeredHorizontally, animated: true)
let main = ViewController()
if let tableViewcell = superview?.superview as? ExploreTableViewCell {
let indexPath = main.tableView.indexPath(for: tableViewcell)
print(indexPath)
}
}
To an extension of Subramanian Mariappan's concept and using delegate pattern to get informed in UIViewController about selection in collection view cell, please check your solution at https://github.com/sauvikapple/StackoverflowQ63802523.
Refactoring this viewController is on my todo list, but this should help out.
The key is setCollectionViewDataSourceDelegate() inside of willDisplayCell(). This lets you tap into the cell, and into the collectionView. And you can do something like set the tag to the row number.
TableView Cell:
import UIKit
class CollectionViewInsideTableViewCell: UITableViewCell {
#IBOutlet weak var collectionView: UICollectionView!
override func awakeFromNib() {
super.awakeFromNib()
collectionView.register(UINib(nibName: "cellNibName", bundle: nil), forCellWithReuseIdentifier: "cellIdentifier")
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
}
func setCollectionViewDataSourceDelegate(dataSourceDelegate: UICollectionViewDataSource & UICollectionViewDelegate, forSection section: Int, multipleSelection: Bool) {
collectionView.delegate = dataSourceDelegate
collectionView.dataSource = dataSourceDelegate
collectionView.allowsSelection = true // If Needed
collectionView.allowsMultipleSelection = multipleSelection // If Needed
collectionView.scrollToItem(at: IndexPath(item: 31, section: 0), at: .right, animated: false)
self.collectionView.layoutSubviews()
}
}
Implementation:
cellforRow() {
let collectionCell = CollectionViewInsideTableViewCell // ETC
return collectionCell
}
extension TableViewController: UICollectionViewDelegate, UICollectionViewDataSource {
override func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
guard let tableViewCell = cell as? CollectionViewInsideTableViewCell else { return }
tableViewCell.setCollectionViewDataSourceDelegate(dataSourceDelegate: self, forSection: indexPath.section, multipleSelection: true)
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = CollectionViewCell // ETC
return cell
}
Delegate isn't being called from tableViewCell. Here is UICollectionViewDelegate and UICollectionViewDataSource code
extension HomeVC:UICollectionViewDataSource,UICollectionViewDelegate,UICollectionViewDelegateFlowLayout{
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 4
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "ProductCell", for: indexPath)
return cell
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
print("ok")
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let lay = collectionViewLayout as! UICollectionViewFlowLayout
lay.sectionInset = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)
lay.minimumInteritemSpacing = 0
lay.minimumLineSpacing = 0
collectionView.collectionViewLayout = lay
let size = (collectionView.frame.size.width-10) / 2
return CGSize(width: size, height: size)
}
}
swift 5
//MARK:- Tableview Datasource method
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier:"RecentLoanApplicationCell") as! RecentLoanApplicationCell
cell.collectionVC.delegate = self
cell.collectionVC.dataSource = self
cell.btnViewAll.addTarget(self, action: #selector(btnViewALLTap(button:)), for: .touchUpInside)
DispatchQueue.main.async {
cell.collectionVC.reloadData()
}
return cell
}
//MARK:- Tableview Cell in side custom cell Register for collectionView cell
class RecentLoanApplicationCell: UITableViewCell {
#IBOutlet var collectionVC:UICollectionView!
override func awakeFromNib() {
super.awakeFromNib()
self.collectionVC.register(UINib.init(nibName:"RecentLoanCollectionViewCell", bundle: nil), forCellWithReuseIdentifier:"RecentLoanCollectionViewCell")
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
}
}
// Same ControllerView call
//MARK:- Collection DataSource & Delegate
extension HomeViewController : UICollectionViewDelegate,UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 5
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier:"RecentLoanCollectionViewCell", for: indexPath) as! RecentLoanCollectionViewCell
return cell
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
debugPrint("didSelectItemAt ==>\(indexPath.row)")
}
Here is the code how I done for same inside TableViewCell using collectionView and performed selection :
Code inside TableView datasource method :
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "BasicCarColorCell", for: indexPath) as! BasicCarColorCell
cell.dataSource = preloads.colors
cell.collectionViewSetup()
cell.delegate = self
return cell
}
Code for TableViewCell:
protocol BasicCarColorCellDelegate {
func colorCell(cell:BasicCarColorCell, didSelect color: Color)
}
class BasicCarColorCell: UITableViewCell {
var dataSource = Array<Color>()
var selectedColor = Color()
#IBOutlet weak var textView: RSKPlaceholderTextView!
#IBOutlet weak var guideLineMessage:UILabel!
#IBOutlet weak var collectionView: UICollectionView!
var delegate: BasicCarColorCellDelegate?
override func awakeFromNib() {
super.awakeFromNib()
// Initialization code
}
func collectionViewSetup() {
let nib = UINib(nibName: "BasicCarColorCollectionCell", bundle: nil)
self.collectionView.register(nib, forCellWithReuseIdentifier: "BasicCarColorCollectionCell")
let flowLayout = UICollectionViewFlowLayout()
flowLayout.minimumLineSpacing = 0
flowLayout.minimumInteritemSpacing = 0
flowLayout.scrollDirection = .horizontal
collectionView.collectionViewLayout = flowLayout
collectionView.dataSource = self
collectionView.delegate = self
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
// Configure the view for the selected state
}
}
extension BasicCarColorCell: UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return self.dataSource.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "BasicCarColorCollectionCell", for: indexPath) as! BasicCarColorCollectionCell
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let height = collectionView.bounds.size.height-2
let width = height-20
return CGSize(width: width, height:height)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
return UIEdgeInsets(top: 1, left: 10, bottom: 1, right: 10)
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
let color = self.dataSource[indexPath.item]
self.selectedColor = color
delegate?.colorCell(cell: self, didSelect: self.selectedColor)
collectionView.reloadData()
}
}
And to handle the selection of collectionView just implement the method of custom protocol written in TableViewCell in ViewController:
func colorCell(cell: BasicCarColorCell, didSelect color: Color) {
//self.selectedCarColor = color.value
}
You can do it in same pattern as per your need.
Hope it'll help!
You need to set datasource and delegate for collectionView, every time in Tableview delegate CellForRowAtIndexPath.
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 have a TableView and in that UITableViewCell I have a UICollectionView.
Now in my collectionView For each collectionViewCell there is a create cell and remove cell button option. So for create cell I have to go for CreateViewController and for delete button I have to delete respective collectionViewCell.
import UIKit
class TableCollectionCell: UITableViewCell {
#IBOutlet weak var collectionView: UICollectionView!
override func awakeFromNib() {
super.awakeFromNib()
//collectionView cell
collectionView!.register(UINib(nibName: "CreateGroupCell", bundle: nil), forCellWithReuseIdentifier: "CreateGroupCell")
}
override func setSelected(_ selected: Bool, animated: Bool) {
super.setSelected(selected, animated: animated)
}
}
//Collection View
extension TableCollectionCell : UICollectionViewDataSource ,UICollectionViewDelegateFlowLayout
{
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int
{
return 4
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell
{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CreateGroupCell", for: indexPath) as! CreateGroupCell
cell.groupName.text = ""
CreateCardView(viewCorner: cell.cardView)
if(0 == indexPath.row)
{
//cell.btnDotted.tag = indexPath.row
//cell.btnShare.tag = indexPath.row
cell.btnDotted.setImage(UIImage(named: "Info"), for: UIControlState.normal)
cell.btnShare.setImage(UIImage(named : "AddGroup"), for: UIControlState.normal)
}
else if(indexPath.row >= 1 && indexPath.row <= 3)
{
cell.btnDotted.isHidden = true
cell.btnShare.isHidden = true
cell.groupImage.image = UIImage(named: "group_dull_card.png")
}
else
{
}
return cell
}
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
if ( 0 == indexPath.row) {
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 200, height: 150)
}
}
Now in my didSelectRow method if (indexPath.row == 0) then I have to go for CreateViewController.
How can I do that? I am new in delegate also.
didSelectRow method
if ( indexPath.row == 0)
{
self.storyboard?.instantiateViewControllerWithIdentifier("CreateViewControllerid") as! CreateViewController.
self.navigationController?.pushViewController(secondViewController, animated: true)
}