Handle view component events inside UICollectionView Cell

ChallengeViewController.swift

//
//  ChallengeViewController.swift
//  Challenge
//
//  Created by Coder ACJHP on 27.06.2019.
//  Copyright © 2019 Fitbest Bilgi Teknolojileri. All rights reserved.
//

import UIKit

extension UICollectionView {

    var centerPoint : CGPoint {

        get {
            return CGPoint(x: self.center.x + self.contentOffset.x, y: 45);
        }
    }

    var centerCellIndexPath: IndexPath? {

        return self.indexPathForItem(at: centerPoint)
    }
}

var globalCounter: Int = 0

class ChallengeCell: UICollectionViewCell {
    
    public var color: UIColor = .orange {
        didSet {
            self.backgroundColor = color
        }
    }
    
    private lazy var actionButton: UIButton = {
        let btn = UIButton(type: .system)
        btn.backgroundColor = UIColor.lightGray
        btn.layer.cornerRadius = 5
        btn.layer.masksToBounds = true
        btn.setTitle("Press Me!", for: .normal)
        btn.setTitle("Press Me!", for: .selected)
        btn.setTitleColor(.black, for: .normal)
        btn.setTitleColor(.black, for: .selected)
        btn.titleLabel?.font = UIFont.boldSystemFont(ofSize: 18)
        btn.translatesAutoresizingMaskIntoConstraints = false
        btn.addTarget(self, action: #selector(hanldePress(_:)), for: .touchUpInside)
        return btn
    }()
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        commonInit()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        
        commonInit()
    }
    
    private func commonInit() {
        
        self.layer.cornerRadius = 7
        self.layer.masksToBounds = true
        
        self.addSubview(actionButton)
        actionButton.widthAnchor.constraint(equalToConstant: 120).isActive = true
        actionButton.heightAnchor.constraint(equalToConstant: 45).isActive = true
        actionButton.centerYAnchor.constraint(equalTo: centerYAnchor).isActive = true
        actionButton.centerXAnchor.constraint(equalTo: centerXAnchor).isActive = true
    }
    
    override func prepareForReuse() {
        super.prepareForReuse()
        
    }
    
    @objc public func hanldePress(_ sender: UIButton) {
        globalCounter += 1
        print("ChallengeCell action button pressed with event 'touchUpInside' \nTotal press count: \(globalCounter)")
    }
}

class ChallengeViewController: UIViewController, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {

    private let challengeCellId: String = "reusableChallengeCellId"
    
    // MARK: - Public elements
    public lazy var challengeCollectionView: UICollectionView = {
        let flowLayout = UICollectionViewFlowLayout()
        flowLayout.scrollDirection = .horizontal
        let collectionView = UICollectionView(frame: .zero, collectionViewLayout: flowLayout)
        collectionView.backgroundColor = .clear
        collectionView.register(ChallengeCell.self, forCellWithReuseIdentifier: challengeCellId)
        collectionView.showsVerticalScrollIndicator = false
        collectionView.showsHorizontalScrollIndicator = false
        collectionView.translatesAutoresizingMaskIntoConstraints = false
        return collectionView
    }()
    public var challengeList: [Int] = Array(0...4)
    public var challengeColorList: [UIColor] = [
        .init(hexString: "#ead777"), .init(hexString: "#8d5de6"),
        .init(hexString: "#484af3"),  .init(hexString: "#e85cc3"), .orange
    ]
    
    private lazy var pageDotView: UIPageControl = {
        let control = UIPageControl(frame: .zero)
        control.numberOfPages = challengeList.count
        control.currentPage = 0
        control.pageIndicatorTintColor = UIColor(white: 1, alpha: 0.5)
        control.currentPageIndicatorTintColor = .white
        control.translatesAutoresizingMaskIntoConstraints = false
        return control
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .purple
        
        // Digit CollectionView
        challengeCollectionView.delegate = self
        challengeCollectionView.dataSource = self
        view.addSubview(challengeCollectionView)
        
        challengeCollectionView.widthAnchor.constraint(equalToConstant: view.bounds.width).isActive = true
        challengeCollectionView.heightAnchor.constraint(equalToConstant: 190).isActive = true
        challengeCollectionView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        challengeCollectionView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
        
        view.addSubview(pageDotView)
        pageDotView.topAnchor.constraint(equalTo: challengeCollectionView.bottomAnchor, constant: 5).isActive = true
        pageDotView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
    }
    
    //MARK: - Collection view delegate & dataSource
    func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return challengeList.count
    }
    
    func collectionView(_ collectionView: UICollectionView,
                        cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        
        guard let challengeCell = collectionView.dequeueReusableCell( withReuseIdentifier: challengeCellId,
                                                                      for: indexPath) as? ChallengeCell else
                                                                        { return UICollectionViewCell() }
        
        challengeCell.color = challengeColorList[indexPath.item]
        return challengeCell
    }
    
    func collectionView(_ collectionView: UICollectionView,
                        didSelectItemAt indexPath: IndexPath) {
        guard let selectedCell = collectionView.cellForItem(at: indexPath) as? DigitCell else { return }
        print(selectedCell.range)
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        return 20
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
        return 20
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return .init(width: view.bounds.width - 50, height: 170)
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        return .init(top: 0, left: 30, bottom: 0, right: 30)
    }
    
    func scrollViewDidScroll(_ scrollView: UIScrollView) {
        
        guard let centerIndexPath = challengeCollectionView.centerCellIndexPath else { return }
        pageDotView.currentPage = centerIndexPath.item
    }

}