An object that manages an ordered collection of data items and presents them using customizable layouts. When you add a collection view to your user interface, your app's main job is to manage the data associated with that collection view. The collection view gets its data from the data source object, stored in the collection view’s dataSource property. For your data source, you can create a custom data source object by adopting the UICollectionViewDataSource protocol.
class Emoji {
enum Category: String, CaseIterable {
case smileysAndPeople = "Smileys & People"
case animalsAndNature = "Animals & Nature"
case foodAndDrink = "Food & Drink"
case activity = "Activity"
case travelAndPlaces = "Travel & Places"
case objects = "Objects"
case symbols = "Symbols"
case flags = "Flags"
}
static let shared = Emoji()
let sections = Category.allCases
var data: [Category: [String]] = [
.smileysAndPeople: ["😀", "😃", "😄", "😁", "😆", "😅", "😂", "🤣", "☺️", "😊", "🤯", "😇", "🙂", "😎", "🤩", "😴", "😬", "🥵"],
.animalsAndNature: ["🐶", "🐱", "🦊", "🐻", "🦁", "🐮", "🐸", "🐵", "🐔", "🐧", "🦉", "🐴", "🦋", "🐙", "🐬", "🐈", "🌲", "🌍"],
.foodAndDrink: ["🍏", "🍇", "🍓", "🥝", "🍅", "🌽", "🥕", "🥨", "🧀", "🍖", "🦴", "🌮", "🍣", "🥤", "🥃", "🥟", "🍺", "🍪"],
.activity: ["⚽️", "🏉", "🥏", "🏏", "🥅", "🛹", "🛷", "🏋️♂️", "🏅", "🎪", "🎬", "🎼", "🎲", "🎳", "🎮", "🎸", "🧩", "🏆"],
.travelAndPlaces: ["🚗", "🚑", "🚨", "🚠", "🚟", "🚄", "✈️", "🚤", "🚧", "🏠", "⛱", "🌋", "⛩", "🕋", "⛪️", "🌠", "🌇", "🗽"],
.objects: ["⌚️", "🖱", "🖲", "💾", "☎️", "📺", "💴", "🔨", "🧰", "🧲", "🎁", "🎊", "✉️", "🗳", "📌", "🔍", "🔐", "💰"],
.symbols: ["❤️", "💔", "☮️", "☯️", "☢️", "🆚", "🉐", "🆘", "❌", "💯", "‼️", "🚸", "⚜️", "♿️", "🔈", "🔔", "♣️", "🚸"],
.flags: ["🏳️", "🇺🇸", "🇯🇵", "🇩🇪", "🇨🇦", "🇲🇽", "🇧🇷", "🇰🇪", "🇳🇬", "🇮🇳", "🇷🇺", "🇦🇺", "🇫🇷", "🇵🇱", "🇻🇳", "🇱🇹", "🇱🇰", "🇪🇪"]
]
private init() {}
static func randomEmoji() -> (Category, String) {
let extraEmoji = ["💀", "🤖", "👍", "🤘🏾", "🖐🏼", "👇🏽", "🙏🏾", "👀", "👩🏽🦱", "👩🏿", "🧕🏽", "🕵🏻♂️", "👨🏼💻", "👭", "🧚🏾♂️", "💍"]
let randomIndex = Int.random(in: 0..<extraEmoji.count)
return (.smileysAndPeople, extraEmoji[randomIndex])
}
func emoji(at indePath: IndexPath) -> String?
{
let catagory = sections[indePath.section]
return data[catagory]?[indePath.item]
}
}import UIKit
class DataSource: NSObject, UICollectionViewDataSource {
let emoji = Emoji.shared
func numberOfSections(in collectionView: UICollectionView) -> Int {
emoji.sections.count
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
let catagory = emoji.sections[section]
let emoji = self.emoji.data[catagory]
return emoji?.count ?? 0
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
guard let emojiCell = collectionView.dequeueReusableCell(withReuseIdentifier: EmojiCell.reuseIdentifier, for: indexPath) as? EmojiCell else {
fatalError("Cell cannot be created")
}
let catagory = emoji.sections[indexPath.section]
let emoji = self.emoji.data[catagory]?[indexPath.item] ?? ""
emojiCell.emojiLabel.text = emoji
return emojiCell
}
func collectionView(_ collectionView: UICollectionView, viewForSupplementaryElementOfKind kind: String, at indexPath: IndexPath) -> UICollectionReusableView {
guard let emojiHeaderView = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: EmojiHeaderView.reuseIdentifier, for: indexPath) as? EmojiHeaderView else {
fatalError("Cannot create EmojiHeader")
}
let catagory = emoji.sections[indexPath.section]
emojiHeaderView.textLabel.text = catagory.rawValue
return emojiHeaderView
}
}
extension DataSource {
func addEmoji(_ emoji: String, to catagory: Emoji.Category) {
guard var emojiData = self.emoji.data[catagory] else {
return
}
emojiData.append(emoji)
self.emoji.data.updateValue(emojiData, forKey: catagory)
}
func deleteEmoji(at indexPath: IndexPath) {
let catagory = emoji.sections[indexPath.section]
guard var emojiData = emoji.data[catagory] else {
return
}
emojiData.remove(at: indexPath.item)
emoji.data.updateValue(emojiData, forKey: catagory)
}
func deleteEmoji(at indexPaths: [IndexPath]) {
for path in indexPaths {
deleteEmoji(at: path)
}
}
}import UIKit
class EmojiCollectionViewDelegate: NSObject, UICollectionViewDelegateFlowLayout {
let numbrOfItemsPerRow: CGFloat
let interItemSpacing: CGFloat
init(numbrOfItemsPerRow: CGFloat, interItemSpacing: CGFloat) {
self.numbrOfItemsPerRow = numbrOfItemsPerRow
self.interItemSpacing = interItemSpacing
}
// set the size of items
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let maxWidth = UIScreen.main.bounds.width
let totalSpacing = interItemSpacing * numbrOfItemsPerRow
let itemWidth = (maxWidth - totalSpacing)/numbrOfItemsPerRow
return CGSize(width: itemWidth, height: itemWidth)
}
// spacing between successive items of a single row
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return interItemSpacing
}
// margin sizes or return different margin sizes for each section
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
if section == 0 {
return UIEdgeInsets(top: 0, left: 0, bottom: interItemSpacing/2, right: 0)
}
return UIEdgeInsets(top: interItemSpacing/2, left: 0, bottom: interItemSpacing/2, right: 0)
}
}
import UIKit
class EmojiHeaderView: UICollectionReusableView {
static let reuseIdentifier = String(describing: EmojiHeaderView.self)
@IBOutlet weak var textLabel: UILabel!
}import UIKit
class EmojiCell: UICollectionViewCell {
static let reuseIdentifier = String(describing: EmojiCell.self)
@IBOutlet weak var emojiLabel: UILabel!
var isEditing: Bool = false
override var isSelected: Bool {
didSet {
if isEditing {
contentView.backgroundColor = isSelected ? UIColor.systemRed.withAlphaComponent(0.5) : UIColor.systemGroupedBackground
} else {
contentView.backgroundColor = UIColor.systemGroupedBackground
}
}
}
}import UIKit
class ViewController: UIViewController {
@IBOutlet weak var collectionView: UICollectionView!
@IBOutlet weak var deleteButton: UIBarButtonItem!
@IBOutlet weak var addButton: UIBarButtonItem!
let dataSource = DataSource()
let delegate = EmojiCollectionViewDelegate(numbrOfItemsPerRow: 6, interItemSpacing: 8)
override func viewDidLoad() {
super.viewDidLoad()
collectionView.dataSource = dataSource
collectionView.delegate = delegate
collectionView.allowsMultipleSelection = true
navigationItem.leftBarButtonItem = editButtonItem
}
override func setEditing(_ editing: Bool, animated: Bool) {
super.setEditing(editing, animated: animated)
deleteButton.isEnabled = isEditing
addButton.isEnabled = !isEditing
collectionView.indexPathsForVisibleItems.forEach {
guard let emojiCell = collectionView.cellForItem(at: $0) as? EmojiCell else {
return
}
emojiCell.isEditing = editing
}
if isEditing {
collectionView.indexPathsForSelectedItems?.compactMap({ $0 }).forEach {
collectionView.deselectItem(at: $0, animated: true)
}
return
}
}
override func shouldPerformSegue(withIdentifier identifier: String, sender: Any?) -> Bool {
if isEditing && identifier == "showEmojiDetail" {
return false
}
return true
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
guard segue.identifier == "showEmojiDetail",
let emojiCell = sender as? EmojiCell,
let emojiDetailController = segue.destination as? EmojiDetailController,
let indexPath = collectionView.indexPath(for: emojiCell),
let emoji = Emoji.shared.emoji(at: indexPath) else {
fatalError()
}
emojiDetailController.emoji = emoji
}
@IBAction func addEmoji(_ sender: Any) {
let (catagory, randomEmoji) = Emoji.randomEmoji()
dataSource.addEmoji(randomEmoji, to: catagory)
let emojiCount = collectionView.numberOfItems(inSection: 0)
let insertedIndex = IndexPath(item: emojiCount, section: 0)
collectionView.insertItems(at: [insertedIndex])
}
@IBAction func deleteEmoji(_ sender: Any) {
guard let selectedIndices = collectionView.indexPathsForSelectedItems else {
return
}
let sectionsToDelete = Set(selectedIndices.map({ $0.section }))
sectionsToDelete.forEach { section in
let indexPathsForSection = selectedIndices.filter({ $0.section == section})
let sortedIndexPaths = indexPathsForSection.sorted(by: { $0.item > $1.item })
dataSource.deleteEmoji(at: sortedIndexPaths)
collectionView.deleteItems(at: sortedIndexPaths)
}
}
}