I made the gallery using UICollectionView.
If you lower the screen, the image should continue to come out and stop at 20.
The code was constantly updated.
However, the function collectionView (_: layout: sizeForItemAt :) that sets the size of the cell did not work.
Therefore, only 20 images are displayed continuously.
On viewDidLoad()
if let layoutt = artCollectionView?.collectionViewLayout as? PinterestLayout
{
layoutt.delegate = self
}
cell setting
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell
{
guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "HomeCollectionViewCell", for: indexPath) as? HomeCollectionViewCell,
let arts = self.artList else { return HomeCollectionViewCell() }
if arts.count > indexPath.row
{
let model = arts[indexPath.row]
cell.imgView.sd_setImage(with: URLHelper.createEncodedURL(url: model.thumburl), completed: nil)
}
return cell
}
return cell size
extension HomeViewController : PinterestLayoutDelegate
{
func collectionView(_ collectionView: UICollectionView, heightForPhotoAtIndexPath indexPath:IndexPath) -> CGFloat
{
return CGFloat(300.0)
}
}
Currently, the function only executes once when the app starts. Do you know how to run that function every time I want?
You need to implement UICollectionViewDelegateFlowLayout.
You can read more about the protocol here:
UICollectionViewDelegateFlowLayout protocol
Example:
extension viewController: UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 50, height: 300)
}
}
If you look at the prepare() method of PinterestLayout class, you can see the below code
guard
cache.isEmpty == true,
let collectionView = collectionView
else {
return
}
When you reload the colectionView the cache is no longer empty, so it returns back without altering the layout.
So just remove the cache value when prepare is called.
Add removeAll() before guard
cache.removeAll()
Please follow the steps to install PinterestLayout in UICollectionView below.
Set PinterestLayout to your collection view.
let layout = PinterestLayout()
collectionView.collectionViewLayout = layout
Setup layout
layout.delegate = self
layout.cellPadding = 5
layout.numberOfColumns = 2
Implement methods of PinterestLayoutDelegate
extension CustomCollectionVC: PinterestLayoutDelegate {
func collectionView(collectionView: UICollectionView,
heightForImageAtIndexPath indexPath: IndexPath,
withWidth: CGFloat) -> CGFloat {
let image = images[indexPath.item]
return image.height(forWidth: withWidth)
}
func collectionView(collectionView: UICollectionView,
heightForAnnotationAtIndexPath indexPath: IndexPath,
withWidth: CGFloat) -> CGFloat {
let textFont = UIFont(name: "Arial-ItalicMT", size: 11)!
return "Some text".heightForWidth(width: withWidth, font: textFont)
}
}
When data is loaded invalidate layout as well as reload data on collection view.
collectionView.collectionViewLayout.invalidateLayout()
collectionView.reloadData()
Observation:
func collectionView(_ collectionView: UICollectionView, heightForPhotoAtIndexPath indexPath:IndexPath) -> CGFloat
try this instead of above:
func collectionView(collectionView: UICollectionView,
heightForImageAtIndexPath indexPath: IndexPath,
withWidth: CGFloat) -> CGFloat
Related
I have a UICollectionView with a horizontal scroll that shows 3 cells for each page but when I get to the last page there is only one element and it does not let me scroll to show this last element.
This is my list:
var benefitIcons = ["ic_benefit_frappe", "ic_benefit_birthday", "ic_benefit_2x1", "ic_benefit_points", "ic_benefit_combo", "ic_benefit_cine", "ic_benefit_tickets", "ic_benefit_refill", "ic_benefit_klic", "ic_benefit_pay"]
This is the method for UICollectionView:
extension ProfileCCViewController: UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return benefitIcons.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
if let cell = benefitCollection.dequeueReusableCell(withReuseIdentifier: "BenefitCell", for: indexPath) as? UserBenefitsCell {
cell.benefitIcon.image = UIImage(named: benefitIcons[indexPath.row])
cell.benefitLbl.text = benefitDescriptions[indexPath.row]
return cell
} else {
return UICollectionViewCell()
}
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: collectionView.bounds.width/3, height: collectionView.bounds.height)
}
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
benefitControl.currentPage = indexPath.row
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let offSet = scrollView.contentOffset.x
let width = scrollView.frame.width
let horizontalCenter = width / 2
benefitControl.currentPage = Int(offSet + horizontalCenter) / Int(width)
}
}
This how look like correctly:
But when I'm scrolling to the last item and is uneven doesn't scroll to this last section:
I have problem with lottie animations, I have some kind of onboarding on my app and what I would like to achive is to everytime view in collectionview is changed, to start my animation, I have 4 pages and 4 different lottie animations. Currently if I call animation.play() function, once app is started, all of my animations are played at the same time, so once I get to my last page, animation is over. And I want my lottie to be played only once, when view is shown.
This is my cell
class IntroductionCollectionViewCell: UICollectionViewCell {
#IBOutlet var title: UILabel!
#IBOutlet var subtitleDescription: UILabel!
#IBOutlet var animationView: AnimationView!
override func awakeFromNib() {
super.awakeFromNib()
}
public func configure(with data: IntroInformations) {
let animation = Animation.named(data.animationName)
title.text = data.title
subtitleDescription.text = data.description
animationView.animation = animation
}
static func nib() -> UINib {
return UINib(nibName: "IntroductionCollectionViewCell", bundle: nil)
}
}
This is how my collection view is set up
extension IntroductionViewController {
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
pages.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "IntroductionCollectionViewCell", for: indexPath) as! IntroductionCollectionViewCell
cell.configure(with: pages[indexPath.row])
cell.animationView.loopMode = .loop
cell.animationView.play()
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: view.frame.width, height: view.frame.height)
}
func scrollViewDidScroll(_ scrollView: UIScrollView) {
let scrollPos = scrollView.contentOffset.x / view.frame.width
self.pageControl.currentPage = Int(floorf(Float(scrollPos)))
let n = pageControl.numberOfPages
if self.pageControl.currentPage == n - 1 {
continueButton.isHidden = false
} else {
continueButton.isHidden = true
}
}
}
Thanks in advance!!
You can use the collectionViewDelegate willDisplay and didEndDisplaying methods to start/stop the animations. And not when configuring the cell. - https://developer.apple.com/documentation/uikit/uicollectionviewdelegate
If you want the animation to run only once dont use the loop option.
if let cell = cell as? IntroductionCollectionViewCell {
cell.animationView.loopMode = .playOnce
cell.animationView.play()
}
this is the answer, I need to check is cell once is loaded my cell where lottie animation is
I have trying to make a program that will display the image of crystals. After writing the code and formatting the StoryBoard, when I run the app the images are tiny and there are no labels displayed. I have constraints.
Here is the code:
import UIKit
class ViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource {
let imageArray = [UIImage(named: "1"),UIImage(named: "2"),UIImage(named: "3")]
let nameArray = ["Rose Quartz", "Clear Quartz", "Clear Quartz 2"]
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return imageArray.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "MainCollectionViewCell", for: indexPath) as! MainCollectionViewCell
cell.crystalPhotoImageView.image = imageArray[indexPath.row]
cell.crystalNameLabel.text! = nameArray[indexPath.row]
return cell
}
}
you need to implement to confirm the class has UICollectionViewDelegateFlowLayout and you need to implement this functionn
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return cellSize
}
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.
I'm building a survey app and I want to use such view
in this example there's only two answer possible but I want to be possible to have like 3 / 4 answer and different kind of survey,
I will receive a JSON to build it with the type of the question and the answer possible etc ..
My main problem is that I don't really know how to proceed, I'm a newbie on iOS development atm and I don't want to try too many thing and have spaghetti code so if someone have an idea on how to do this collection view with different view depending on the json
Thanks o/
There is lot of ways to achieve it but as in your case you want with Collectionview with multiple different collection viewcell
In ViewController.swift, conform few UICollectionView protocol.
class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate , UICollectionViewDelegateFlowLayout{
#IBOutlet weak var mainCollectionView: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
mainCollectionView.isScrollEnabled = false
}
then implement collection view data source and delegate methods.
// MARK: - UICollectionViewDataSource protocol
// tell the collection view how many cells to make
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 3
}
// make a cell for each cell index path
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
print("indexPath.row \(indexPath.row)")
if indexPath.row == 0{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "firstCell", for: indexPath)
if let button = cell.contentView.viewWithTag(2) as? UIButton{
button.addTarget(self, action: #selector(MoveToNextCell), for: .touchUpInside)
}
return cell
}
else if indexPath.row == 1{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "secondCell", for: indexPath)
if let button = cell.contentView.viewWithTag(3) as? UIButton{
button.addTarget(self, action: #selector(MoveToNextCell), for: .touchUpInside)
}
return cell
}
else{
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "thirdCell", for: indexPath)
if let button = cell.contentView.viewWithTag(4) as? UIButton{
button.addTarget(self, action: #selector(MoveToNextCell), for: .touchUpInside)
}
return cell
}
}
// MARK: - UICollectionViewDelegate protocol
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
// handle tap events
print("You selected cell #\(indexPath.item)!")
}
then implement UICollectionViewDelegateFlowLayout methods.
func collectionView(_ collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: self.view.frame.width , height: self.view.frame.height)
}
func collectionView(_ collectionView: UICollectionView,
layout collectionViewLayout: UICollectionViewLayout,
minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 1.0
}
func collectionView(_ collectionView: UICollectionView, layout
collectionViewLayout: UICollectionViewLayout,
minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 1.0
}
Then finally for moving between cells
func MoveToNextCell(){
let collectionBounds = self.mainCollectionView.bounds
let contentOffset = CGFloat(floor(self.mainCollectionView.contentOffset.x + collectionBounds.size.width))
self.moveToCell(contentOffset: contentOffset)
}
func moveToPreviousCell(){
let collectionBounds = self.mainCollectionView.bounds
let contentOffset = CGFloat(floor(self.mainCollectionView.contentOffset.x - collectionBounds.size.width))
self.moveToCell(contentOffset: contentOffset)
}
func moveToCell(contentOffset: CGFloat){
let frame: CGRect = CGRect(x : contentOffset ,y : self.mainCollectionView.contentOffset.y ,width : self.mainCollectionView.frame.width,height : self.mainCollectionView.frame.height)
self.mainCollectionView.scrollRectToVisible(frame, animated: true)
}
That's pretty much all you need to achieve that.