MagicCell.swift

import UIKit

let kPadding: CGFloat = 20
let kAnimationDuration: TimeInterval = 0.3
let kAnimationDelay: TimeInterval = 0

let kTextSpacing: CGFloat = 10
let kFondSize: CGFloat = 20

class MagicCell: UITableViewCell {
    
    var model: ViewData!
    var expandCallback: ((() -> ()) -> ())!
    
    lazy var mainStack: UIStackView = {
        let view = UIStackView()
        view.translatesAutoresizingMaskIntoConstraints = false
        view.axis = .vertical
        view.spacing = kTextSpacing
        
        view.addArrangedSubview(self.summaryLabel)
        view.addArrangedSubview(self.additionalStack)
        return view
    }()
    
    lazy var additionalStack: UIStackView = {
        let view = UIStackView()
        view.translatesAutoresizingMaskIntoConstraints = false
        view.axis = .horizontal
        view.distribution = .equalCentering
        
        view.addArrangedSubview(self.dateLabel)
        view.addArrangedSubview(self.expandButton)
        return view
    }()
    
    lazy var titleLabel: UILabel = {
        let view = UILabel()
        view.translatesAutoresizingMaskIntoConstraints = false
        view.font = .systemFont(ofSize: kFondSize, weight: .bold)
        view.numberOfLines = .zero
        view.lineBreakMode = .byWordWrapping
        return view
    }()
    
    lazy var summaryLabel: UILabel = {
        let view = UILabel()
        view.numberOfLines = .zero
        view.lineBreakMode = .byWordWrapping
        return view
    }()
    
    lazy var dateLabel: UILabel = {
        let view = UILabel()
        view.textColor = .darkGray
        return view
    }()
    
    lazy var expandButton: UIButton = {
        let view = UIButton()
        view.setImage(UIImage(systemName: "ellipsis"), for: .normal)
        view.addTarget(self, action: #selector(expandButtonTap), for: .touchUpInside)
        return view
    }()
    
    // MARK: - Init
    
    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        setupViews()
    }
    
    required init?(coder: NSCoder) {
        fatalError("Not implemented 🙃")
    }
    
    // MARK: - Layout
    
    override func layoutIfNeeded() {
        super.layoutIfNeeded()
        
        NSLayoutConstraint.activate([
            titleLabel.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: kPadding),
            titleLabel.topAnchor.constraint(equalTo: contentView.topAnchor, constant: kPadding),
            titleLabel.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -kPadding),
            titleLabel.bottomAnchor.constraint(lessThanOrEqualTo: mainStack.topAnchor, constant: -kPadding),
            
            mainStack.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: kPadding),
            mainStack.topAnchor.constraint(equalTo: titleLabel.bottomAnchor, constant: kPadding),
            mainStack.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -kPadding),
            mainStack.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: -kPadding)
        ])
    }
    
    private func setupViews() {
        contentView.addSubview(mainStack)
        contentView.addSubview(titleLabel)
    }
    
    // MARK: -
    
    func configureWithData(_ data: ViewData, completion: @escaping (() -> ()) -> ()) {
        model = data
        expandCallback = completion
        titleLabel.text = data.title
        summaryLabel.text = data.summary
        summaryLabel.isHidden = !data.expanded
        dateLabel.text = data.date
    }
    
    @objc func expandButtonTap() {
        expandCallback({ [unowned self] in
            self.model.expanded.toggle()
            let titleHeight = self.titleLabel.frame.height
            UIView.animateKeyframes(withDuration: kAnimationDuration,
                                    delay: kAnimationDelay,
                                    options: .calculationModeLinear) {
                
                self.titleLabel.heightAnchor.constraint(equalToConstant: titleHeight).isActive = true
                self.summaryLabel.isHidden = !self.model.expanded
            } completion: { (finished) in
                self.titleLabel.heightAnchor.constraint(equalToConstant: titleHeight).isActive = false
            }
        })
    }
}