I am trying to create a program which dynamically updates the collectoinView as the user enters text into the UITextField. Below is the extension I have created to achieve this
I have updated code based on your suggestions to include insert and delete statements,I am still in the process of refactoring and adding delegation but while the code doesn't result in an error it doesn't allow the user to keep typing and closes the keyboard have I implemented everything correctly
Update #2 (Thank you for all of your Help)
import UIKit
class ViewController: UIViewController, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource, UICollectionViewDelegate, UISearchBarDelegate {
lazy var collectionView : UICollectionView = {
let layout = UICollectionViewFlowLayout()
let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
cv.backgroundColor = .white
cv.delegate = self
cv.dataSource = self
return cv
}()
var genericTagsArray:[String] = ["tag1","tag2","tag3","tag4","tag5","tag6","tag7","tag8","tag9","tag10","tag11","tag12","A","B","C","D","E","F","G","Ab","Abc","za","tag1","tag2","tag3","tag4","tag5","tag6","tag7","tag8","tag9","tag10","tag11","tag12","A","B","C","D","E","F","G","Ab","Abc","za"]
var currentTagsArray:[String] = [String]() {
didSet {
collectionView.reloadData()
}
}
override func viewDidLoad() {
super.viewDidLoad()
self.view.addSubview(collectionView)
collectionView.register(Cell.self, forCellWithReuseIdentifier: "cell")
collectionView.register(Header.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "header")
collectionView.anchor(top: view.safeAreaLayoutGuide.topAnchor, leading: self.view.leadingAnchor, bottom: self.view.bottomAnchor, trailing: self.view.trailingAnchor, padding: .init(top: 30, left: 0, bottom: 30, right: 0))
collectionView.contentInset = UIEdgeInsetsMake(0, 0, 0, 0)
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return currentTagsArray.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! Cell
cell.label.text = currentTagsArray[indexPath.item]
return cell
}
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
let header = collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "header", for: indexPath) as! Header
header.searchBar.delegate = self
return header
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width: collectionView.contentSize.width, height: 75)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: self.view.frame.size.width, height: 50)
}
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
}
func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
self.currentTagsArray = self.genericTagsArray.filter { (text) -> Bool in
return text.contains(searchText.lowercased())
}
}
}
class Cell : UICollectionViewCell {
let label = UILabel()
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func setupViews() {
self.backgroundColor = .gray
self.addSubview(label)
label.anchor(top: self.topAnchor, leading: self.leadingAnchor, bottom: self.bottomAnchor, trailing: self.trailingAnchor)
}
}
class Header: UICollectionReusableView{
var searchBar = UISearchBar(frame: .zero)
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func setupViews() {
self.backgroundColor = .gray
self.addSubview(searchBar)
searchBar.anchor(top: self.topAnchor, leading: self.leadingAnchor, bottom: nil, trailing: self.trailingAnchor, padding: .init(top: 0, left: 5, bottom: 0, right: 5), size: .init(width: 0, height: 50))
}
}
extension UIView {
func anchor(top: NSLayoutYAxisAnchor?, leading: NSLayoutXAxisAnchor?, bottom: NSLayoutYAxisAnchor?, trailing: NSLayoutXAxisAnchor?, padding: UIEdgeInsets = .zero, size: CGSize = .zero) {
translatesAutoresizingMaskIntoConstraints = false
if let top = top {
topAnchor.constraint(equalTo: top, constant: padding.top).isActive = true
}
if let leading = leading {
leadingAnchor.constraint(equalTo: leading, constant: padding.left).isActive = true
}
if let bottom = bottom {
bottomAnchor.constraint(equalTo: bottom, constant: -padding.bottom).isActive = true
}
if let trailing = trailing {
trailingAnchor.constraint(equalTo: trailing, constant: -padding.right).isActive = true
}
if size.width != 0 {
widthAnchor.constraint(equalToConstant: size.width).isActive = true
}
if size.height != 0 {
heightAnchor.constraint(equalToConstant: size.height).isActive = true
}
}
}
Updated Function With Edits
#objc func textFieldDidChange(){
guard(!(feedSearchBar.text?.isEmpty)!) else{
VC.currentTagsArray = VC.genericTagsArray
VC.feedScreenCollectionView.reloadData()
return
}
VC.currentTagsArray = VC.genericTagsArray.filter({letter -> Bool in
if feedSearchBar.text!.count > letter.count{
return false
}
let stringRange = letter.index(letter.startIndex, offsetBy: feedSearchBar.text!.count)
let subword = letter[..<stringRange]
return subword.lowercased().contains(feedSearchBar.text!.lowercased())
})
if VC.currentTagsArray.isEmpty{
VC.feedScreenCollectionView.deleteItems()
VC.currentTagsArray.insert(feedSearchBar.text!, at: 0)
VC.feedScreenCollectionView.insertItems(at: [IndexPath(item: 0, section: 0)])
//VC.feedScreenCollectionView.reloadItems(inSection: 0)
// VC.feedScreenCollectionView.reloadItems(at: [IndexPath(item: 0, section: 0)])
}
//VC.feedScreenCollectionView.reloadData()
VC.feedScreenCollectionView.reloadItems(inSection: 0)
}
extension UICollectionView{
func reloadItems(inSection section:Int = 0) {
var indicies:[IndexPath] = [IndexPath]()
print("current number of items to reload \(self.numberOfItems(inSection: section))")
for i in 0..<self.numberOfItems(inSection: section){
indicies.append(IndexPath(item: i, section: section))
print("current item number: \(i)")
}
self.reloadItems(at: indicies)
// self.insertItems(at: indicies)
}
func deleteItems(inSection section:Int = 0){
var indicies:[IndexPath] = [IndexPath]()
for i in 0..<self.numberOfItems(inSection: section){
indicies.append(IndexPath(item: i, section: section))
}
self.deleteItems(at: indicies)
}
}
Original Function:
extension UICollectionView{
func reloadItems(inSection section:Int = 0) {
var indicies:[IndexPath] = [IndexPath]()
for i in 0..<self.numberOfItems(inSection: section){
indicies.append(IndexPath(item: i, section: section))
}
self.reloadItems(at: indicies)
}
}
However when ever I call this function after the textField has been edited the program crashes with the error
* Assertion failure in -[UICollectionView _endItemAnimationsWithInvalidationContext:tentativelyForReordering:animator:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit_Sim/UIKit-3698.54.4/UICollectionView.m:5867
2018-07-18 16:28:02.226606-0400 FeedScreenReuseableView[87752:9704142] * Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'attempt to insert item 6 into section 0, but there are only 6 items in section 0 after the update'
I am not sure how to fix this. Is there a better way to go about reloading cells that does not affect the header. Thank you for all of your help in advance. Below is the code from the project in its entirety.
import UIKit
class ViewController: UIViewController,UICollectionViewDelegateFlowLayout,UICollectionViewDelegate,UICollectionViewDataSource,printDelegateWorkedDelegate,updateCollectionView{
func updateCollectionView() {
self.feedScreenCollectionView.reloadData()
}
func printDelegateWorkedDelegate() {
print("The delegate worked")
}
var genericTagsArray:[String] = ["tag1","tag2","tag3","tag4","tag5","tag6","tag7","tag8","tag9","tag10","tag11","tag12","A","B","C","D","E","F","G","Ab","Abc","za","tag1","tag2","tag3","tag4","tag5","tag6","tag7","tag8","tag9","tag10","tag11","tag12","A","B","C","D","E","F","G","Ab","Abc","za"]
var currentTagsArray:[String] = [String]()
var tagsSelected:[String] = [String]()
let keyboardSlider = KeyboardSlider()
var header:feedViewHeader = feedViewHeader()
#IBOutlet weak var feedScreenCollectionView: UICollectionView!
override func viewDidLoad() {
super.viewDidLoad()
keyboardSlider.subscribeToKeyboardNotifications(view: view)
currentTagsArray = genericTagsArray
let viewTapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(feedViewHeader.viewTapped(gestureRecognizer:)))
viewTapGestureRecognizer.cancelsTouchesInView = false
self.feedScreenCollectionView.addGestureRecognizer(viewTapGestureRecognizer)
feedScreenCollectionView.delegate = self
//
feedScreenCollectionView.dataSource = self
//
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.sectionInset = UIEdgeInsets(top: 5, left: 1, bottom: 0, right: 1)
layout.minimumLineSpacing = 0
layout.headerReferenceSize = CGSize(width: 50, height: 75)
layout.sectionHeadersPinToVisibleBounds = true
feedScreenCollectionView.collectionViewLayout = layout
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
return CGSize(width: 50, height: 75)
}
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
header = collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "feedViewHeader", for: indexPath) as! feedViewHeader
header.VC = self
return header
}
//
//Data Source
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return currentTagsArray.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "feedViewCell", for: indexPath) as! feedViewCell
cell.feedImageView.backgroundColor = .blue
cell.feedImageView.clipsToBounds = true
cell.feedImageView.layer.cornerRadius = CGFloat((cell.feedImageView.frame.width)/5)
cell.feedLabel.text = currentTagsArray[indexPath.item]
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat{
return 0
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let collectionViewWidth = collectionView.bounds.width/4.0
let collectionViewHeight = collectionViewWidth
return CGSize(width: collectionViewWidth-4, height: collectionViewHeight+25)
}
var lastContentOffset:CGFloat = 0
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if self.lastContentOffset > self.feedScreenCollectionView.contentOffset.y && self.feedScreenCollectionView.contentOffset.y > 0 && self.feedScreenCollectionView.contentOffset.y < self.feedScreenCollectionView.frame.maxY {
self.lastContentOffset = scrollView.contentOffset.y
header.isHidden = false
}
else if (self.lastContentOffset < self.feedScreenCollectionView.contentOffset.y) && (self.feedScreenCollectionView.contentOffset.y < self.feedScreenCollectionView.frame.maxY) && (self.feedScreenCollectionView.contentOffset.y > 0) {
print("you scrolled down,content offSet: \(scrollView.contentOffset.y)->\(self.feedScreenCollectionView.contentOffset.y)")
header.isHidden = true
}
else{
self.lastContentOffset = scrollView.contentOffset.y
print("content offSet: \(scrollView.contentOffset.y)")
print("Nothing happened")
// self.headerDelegate?.hideHeaderView(hide: true)
}
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
NotificationCenter.default.addObserver(self, selector: #selector(ViewController.keyboardFrameChangeNotification(notification:)), name: NSNotification.Name.UIKeyboardWillChangeFrame, object: nil)
}
var offsetY:CGFloat = 0
#objc func keyboardFrameChangeNotification(notification: Notification) {
}
}
class feedViewCell:UICollectionViewCell{
#IBOutlet weak var feedImageView: UIImageView!
#IBOutlet weak var feedLabel: UILabel!
let keyboardSlider = KeyboardSlider()
override func awakeFromNib() {
super.awakeFromNib()
feedLabel.translatesAutoresizingMaskIntoConstraints = false
feedImageView.topAnchor.constraint(equalTo: self.topAnchor).isActive = true
feedImageView.leadingAnchor.constraint(equalTo: self.leadingAnchor).isActive = true
feedImageView.trailingAnchor.constraint(equalTo: self.trailingAnchor).isActive = true
feedImageView.bottomAnchor.constraint(equalTo: self.feedLabel.topAnchor).isActive = true
feedImageView.translatesAutoresizingMaskIntoConstraints = false
feedLabel.leadingAnchor.constraint(equalTo: self.leadingAnchor).isActive = true
feedLabel.trailingAnchor.constraint(equalTo: self.trailingAnchor).isActive = true
feedLabel.bottomAnchor.constraint(equalTo: self.bottomAnchor).isActive = true
feedLabel.topAnchor.constraint(equalTo: self.feedImageView.bottomAnchor).isActive = true
feedLabel.textAlignment = .center
}
}
class feedViewHeader:UICollectionReusableView,UITextFieldDelegate,UICollectionViewDelegate{
#IBOutlet weak var feedSearchBar: UITextField!
var delegateWorked:printDelegateWorkedDelegate?
var updateCV:updateCollectionView?
var VC:ViewController!
var collectionView:UICollectionView?
var stringToBeSet = "String to be set"
override func awakeFromNib() {
super.awakeFromNib()
feedSearchBar.delegate = self
feedSearchBar.autocorrectionType = .no
feedSearchBar.keyboardType = .default
feedSearchBar.addTarget(self, action: #selector(feedViewHeader.textFieldDidChange), for: .editingChanged)
self.feedSearchBar.borderStyle = .roundedRect
self.feedSearchBar.layer.borderColor = UIColor.black.cgColor
self.feedSearchBar.layer.borderWidth = 4
var searchBarHeight = self.feedSearchBar.bounds.height
self.feedSearchBar.placeholder = "Tap To Search"
self.feedSearchBar.returnKeyType = .search
self.feedSearchBar.rightViewMode = .always
}
#objc func viewTapped(gestureRecognizer:UIGestureRecognizer){
if feedSearchBar.isFirstResponder{
feedSearchBar.resignFirstResponder()
}
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
textField.resignFirstResponder()
VC.feedScreenCollectionView.reloadData()
//VC.feedScreenCollectionView.reloadSections([0])
return true
}
/// Helper to dismiss keyboard
#objc func didStopEditing() {
}
func textFieldDidEndEditing(_ textField: UITextField) {
UIView.setAnimationCurve(UIViewAnimationCurve.easeInOut)
UIView.animate(withDuration: 0.2) {
self.VC.view.frame.origin.y = 0
}
}
#objc func textFieldDidChange(){
guard(!(feedSearchBar.text?.isEmpty)!) else{
VC.currentTagsArray = VC.genericTagsArray
VC.feedScreenCollectionView.reloadData()
return
}
VC.currentTagsArray = VC.genericTagsArray.filter({letter -> Bool in
if feedSearchBar.text!.count > letter.count{
return false
}
let stringRange = letter.index(letter.startIndex, offsetBy: feedSearchBar.text!.count)
let subword = letter[..<stringRange]
return subword.lowercased().contains(feedSearchBar.text!.lowercased())
})
if VC.currentTagsArray.isEmpty{
VC.currentTagsArray.insert(feedSearchBar.text!, at: 0)
}
VC.feedScreenCollectionView.reloadItems(inSection: 0)
}
}
extension Notification.Name{
static let showKeyboard = Notification.Name("showKeyboard")
}
class KeyboardSlider: NSObject {
// variables to hold and process information from the view using this class
weak var view: UIView?
#objc func keyboardWillShow(notification: NSNotification) {
// method to move keyboard up
// view?.frame.origin.y = 0 - getKeyboardHeight(notification as Notification)
print("made it to keyboard will show")
}
func getKeyboardHeight(_ notification:Notification) -> CGFloat {
// get exact height of keyboard on all devices and convert to float value to return for use
let userInfo = notification.userInfo
let keyboardSize = userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue
return keyboardSize.cgRectValue.height
}
func subscribeToKeyboardNotifications(view: UIView) {
// assigning view to class' counterpart
self.view = view
// when UIKeyboardWillShow do keyboardWillShow function
NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(notification:)), name: .UIKeyboardWillShow, object: nil)
}
func unsubscribeFromKeyboardNotifications() {
NotificationCenter.default.removeObserver(self, name: .UIKeyboardWillShow, object: nil)
}
}
class blankView:UICollectionReusableView{
}
extension UICollectionView{
func reloadItems(inSection section:Int = 0) {
print("made it to reload")
for i in 0..<self.numberOfItems(inSection: section){
self.reloadItems(at: [IndexPath(item: i, section: section)])
}
}
}
You are adding a new string to your VC.currentTagsArray but you aren't calling insertItems(at:) on your collection view, so when numberOfItemsInSection suddenly starts returning more items than it did previously you get the consistency exception.
A couple of other observations on style:
I would use delegation to pass events back to the view controller rather than having the header view and cells holding a reference to the VC and tightly coupling the objects.
the variable VC should be vc. Capital first letter is a class
Just call it currentTags not currentTagsArray
Your problem is because you are only calling insertItemsAt, which does exactly that, inserts an item. You are forgetting to deleteItemsAt, which should delete all the items that you don’t want to display any longer.
BTW you should really consider refactoring your code. It is not easy to read and things are not being done in the right place. For example, your header should never be the one in charge of updating your collection view. You should leave that to the controller itself and use delegation to get the text from the header up to the view controller.
Update
Here is an entire code that does the search for you. It is just an example so you can see how it can be done.
import UIKit
class ViewController: UIViewController, UICollectionViewDelegateFlowLayout, UICollectionViewDataSource, UICollectionViewDelegate, UISearchBarDelegate {
lazy var collectionView : UICollectionView = {
let layout = UICollectionViewFlowLayout()
let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
cv.backgroundColor = .white
cv.delegate = self
cv.dataSource = self
return cv
}()
var genericTagsArray:[String] = ["tag1","tag2","tag3","tag4","tag5","tag6","tag7","tag8","tag9","tag10","tag11","tag12","A","B","C","D","E","F","G","Ab","Abc","za","tag1","tag2","tag3","tag4","tag5","tag6","tag7","tag8","tag9","tag10","tag11","tag12","A","B","C","D","E","F","G","Ab","Abc","za"]
var currentTagsArray:[String] = [String]() {
didSet {
collectionView.reloadSections(IndexSet.init(integer: 1))
}
}
override func viewDidLoad() {
super.viewDidLoad()
self.view.addSubview(collectionView)
collectionView.register(Cell.self, forCellWithReuseIdentifier: "cell")
collectionView.register(Header.self, forSupplementaryViewOfKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "header")
collectionView.anchor(top: view.safeAreaLayoutGuide.topAnchor, leading: self.view.leadingAnchor, bottom: self.view.bottomAnchor, trailing: self.view.trailingAnchor, padding: .init(top: 0, left: 0, bottom: 0, right: 0))
collectionView.contentInset = UIEdgeInsetsMake(0, 0, 0, 0)
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
if section == 0 { return 0 }
return currentTagsArray.count
}
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 2
}
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
let header = collectionView.dequeueReusableSupplementaryView(ofKind: UICollectionElementKindSectionHeader, withReuseIdentifier: "header", for: indexPath) as! Header
header.searchBar.delegate = self
return header
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize {
if section == 0 {
return CGSize(width: self.view.frame.width, height: 50)
}
return CGSize()
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! Cell
cell.label.text = currentTagsArray[indexPath.item]
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: self.view.frame.size.width, height: 50)
}
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
}
func searchBar(_ searchBar: UISearchBar, textDidChange searchText: String) {
self.currentTagsArray = self.genericTagsArray.filter { (text) -> Bool in
return text.contains(searchText.lowercased())
}
}
}
class Cell : UICollectionViewCell {
let label = UILabel()
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func setupViews() {
self.backgroundColor = .gray
self.addSubview(label)
label.anchor(top: self.topAnchor, leading: self.leadingAnchor, bottom: self.bottomAnchor, trailing: self.trailingAnchor)
}
}
class Header : UICollectionViewCell {
let searchBar = UISearchBar()
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func setupViews() {
self.backgroundColor = .gray
self.addSubview(searchBar)
searchBar.anchor(top: self.topAnchor, leading: self.leadingAnchor, bottom: self.bottomAnchor, trailing: self.trailingAnchor)
}
}
extension UIView {
func anchor(top: NSLayoutYAxisAnchor?, leading: NSLayoutXAxisAnchor?, bottom: NSLayoutYAxisAnchor?, trailing: NSLayoutXAxisAnchor?, padding: UIEdgeInsets = .zero, size: CGSize = .zero) {
translatesAutoresizingMaskIntoConstraints = false
if let top = top {
topAnchor.constraint(equalTo: top, constant: padding.top).isActive = true
}
if let leading = leading {
leadingAnchor.constraint(equalTo: leading, constant: padding.left).isActive = true
}
if let bottom = bottom {
bottomAnchor.constraint(equalTo: bottom, constant: -padding.bottom).isActive = true
}
if let trailing = trailing {
trailingAnchor.constraint(equalTo: trailing, constant: -padding.right).isActive = true
}
if size.width != 0 {
widthAnchor.constraint(equalToConstant: size.width).isActive = true
}
if size.height != 0 {
heightAnchor.constraint(equalToConstant: size.height).isActive = true
}
}
}
I'm trying to fit 5 UICollectionViewCell's on a single row, and while there seems to be enough horizontal space, there's too much space between each cell. I can't figure out how to reduce it. Here is some pseudo-code along with what it looks like:
class ViewController: UIViewController {
let my_view = MyView()
override func viewDidLoad() {
super.viewDidLoad()
self.my_view.delegate = self
self.my_view.translatesAutoresizingMaskIntoConstraints = false
self.scroll_view.addSubview(self.my_view)
self.my_view.centerXAnchor.constraint(equalTo: self.view.centerXAnchor).isActive = true
self.my_view.topAnchor.constraint(equalTo: self.view.topAnchor, constant: 20).isActive = true
self.my_view.widthAnchor.constraint(equalTo: self.view.widthAnchor).isActive = true
self.my_view.bottomAnchor.constraint(equalToConstant: 100).isActive = true
}
}
extension ViewController: UICollectionViewDelegateFlowLayout, UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 5
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! MyCell
return cell
}
}
class MyView: UIView {
var delegate: ViewController! {
didSet {
self.collection_view.delegate = self.delegate
self.collection_view.dataSource = self.delegate
}
}
var collection_view: UICollectionView!
init() {
let layout = UICollectionViewFlowLayout()
layout.sectionInset = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)
layout.itemSize = CGSize(width: 60, height: 40)
layout.minimumInteritemSpacing = 0
layout.minimumLineSpacing = 0
self.collection_view = UICollectionView(frame: .zero, collectionViewLayout: layout)
self.collection_view.register(AgeCell.self, forCellWithReuseIdentifier: "cell")
self.collection_view.backgroundColor = .clear
self.collection_view.translatesAutoresizingMaskIntoConstraints = false
self.addSubview(self.collection_view)
self.collection_view.centerXAnchor.constraint(equalTo: self.centerXAnchor).isActive = true
self.collection_view.widthAnchor.constraint(equalTo: self.widthAnchor).isActive = true
self.collection_view.topAnchor.constraint(equalTo: self.title_label.bottomAnchor, constant: 15).isActive = true
self.collection_view.heightAnchor.constraint(equalToConstant: 60).isActive = true
}
}
class MyCell: UICollectionViewCell {
let button: UIButton = {
let button = UIButton(type: .system)
button.backgroundColor = UIColor(r: 0, g: 0, b: 0, a: 100)
button.setTitle("Test", for: .normal)
button.layer.borderColor = UIColor.EVO_blue.cgColor
button.layer.borderWidth = 1.0
return button
}()
override init(frame: CGRect) {
super.init(frame: frame)
self.addSubview(self.button)
self.button.frame = self.frame
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
This is the width of the device, and only 3 show up:
What can I do to get all 5 cells to appear? Thanks.
Use UICollectionViewDelegateFlowLayout, You need to return the correct size in sizeForItemAt method. I'm trying to write the logic to resolve you problem.
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let width = (Globals.screenWidth - 60.0) / 5
return CGSize(width: width, height: 80.0)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
return UIEdgeInsetsMake(0, 5, 0, 5)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 0.0
}
try this.
The problem was that in my MyCell class, I was writing
self.button.frame = self.frame
Whereas I should have written
self.button.frame = self.bounds
Use the UICollectionViewDelegateFlowLayout method for manage the cell size, LineSpacing and InterItemSpacing :-
func collectionView(_ collectionView: UICollectionView, layout
collectionViewLayout: UICollectionViewLayout,
minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
func collectionView(_ collectionView: UICollectionView, layout
collectionViewLayout: UICollectionViewLayout,
minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 0
}
func collectionView(_ collectionView: UICollectionView, layout
collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath:
IndexPath) -> CGSize {
return CGSize // return size of cell according to you
}
I made a class GalleryCollectionViewController that inherited from UICollectionView like this:
import UIKit
class GalleryCollectionViewController: UICollectionViewController {
var dataSourceArr:Array<UIImage>!
override convenience init(collectionViewLayout layout: UICollectionViewLayout) {
self.init()
collectionView?.collectionViewLayout = layout
collectionView!.register(GalleryCollectionViewCell.self, forCellWithReuseIdentifier: "cell")
}
override func viewDidLoad() {
super.viewDidLoad()
}
// MARK: UICollectionViewDataSource
override func numberOfSections(in collectionView: UICollectionView) -> Int {
// #warning Incomplete implementation, return the number of sections
return 1
}
override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
// #warning Incomplete implementation, return the number of items
if dataSourceArr.count != 0 {
return dataSourceArr.count
}
return 0
}
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as! GalleryCollectionViewCell
cell.imageView.image = dataSourceArr[indexPath.row]
return cell
}
GalleryCollectionViewCell has defined.
And in root controller set this in viewDidLoad :
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.sectionInset = UIEdgeInsets(top: 20, left: 10, bottom: 10, right: 10)
layout.itemSize = CGSize(width: 90, height: 120)
let galleryColVC = GalleryCollectionViewController(collectionViewLayout: layout)
galleryColVC.dataSourceArr = photoLibraryImagesArr
self.present(galleryColVC, animated: true, completion: nil)
And but get this error in UICollectionView :
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'UICollectionView must be
initialized with a non-nil layout parameter'
Please help to fix this.
Here is small example
import UIKit
class ViewController: UIViewController {
let cellId = "cellId"
let newCollection: UICollectionView = {
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
let collection = UICollectionView(frame: CGRect(x: 0, y: 0, width: 0, height: 0), collectionViewLayout: layout)
collection.translatesAutoresizingMaskIntoConstraints = false
collection.backgroundColor = UIColor.darkGray
collection.isScrollEnabled = true
// collection.contentSize = CGSize(width: 2000 , height: 400)
return collection
}()
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(newCollection)
newCollection.delegate = self
newCollection.dataSource = self
newCollection.register(CustomeCell.self, forCellWithReuseIdentifier: cellId)
setupCollection()
}
func setupCollection(){
newCollection.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
newCollection.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
newCollection.heightAnchor.constraint(equalToConstant: 400).isActive = true
newCollection.widthAnchor.constraint(equalToConstant: view.frame.width).isActive = true
}
}
extension ViewController: UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout{
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 100
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = newCollection.dequeueReusableCell(withReuseIdentifier: cellId, for: indexPath) as! CustomeCell
cell.backgroundColor = .white
cell.layer.cornerRadius = 5
cell.layer.borderWidth = 2
cell.layer.borderColor = UIColor.white.cgColor
cell.layer.shadowOpacity = 3
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: 150, height: 250)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
return UIEdgeInsets(top: 3, left: 3, bottom: 3, right: 3)
}
}
class CustomeCell: UICollectionViewCell {
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}