UITableViewCell+ClearButton: Adds clear data button to the cell #uikit #swift-api #real-project

UITableViewCell+ClearButton.swift

import UIKit

extension UITableViewCell {
  // MARK: - Public API
  public var fw_onClearButtonTap: (() -> Void)? {
    get { return objc_getAssociatedObject(self, AssociatedKeys.onClearButtonTap) as? () -> Void }
    set {
      objc_setAssociatedObject(self,
                               AssociatedKeys.onClearButtonTap,
                               newValue,
                               .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    }
  }
  
  @objc dynamic public var fw_isClearButtonHidden: Bool {
    get { return fw_clearButton.superview == nil }
    set { setClearButtonHidden(newValue) }
  }
  
  // MARK: - Private API
  private enum AssociatedKeys {
    // Use stable, immutable keys to avoid concurrency warnings
    @MainActor
    static let clearButton: UnsafeRawPointer = {
      UnsafeRawPointer(bitPattern: "fw_clearButton".hashValue)!
    }()
    @MainActor
    static let onClearButtonTap: UnsafeRawPointer = {
      UnsafeRawPointer(bitPattern: "fw_onClearButtonTap".hashValue)!
    }()
  }
  
  private enum Constants {
    static let imageInset: CGFloat = 10
    static let sideMeasure: CGFloat = 40
    static let clearImage = #imageLiteral(resourceName: "ico_cross_circle").withRenderingMode(.alwaysTemplate)
  }
  
  private var fw_clearButton: UIButton {
    if let readonlyButton = objc_getAssociatedObject(self, AssociatedKeys.clearButton) as? UIButton {
      return readonlyButton
    }
    
    let button = createClearButton()
    objc_setAssociatedObject(self,
                             AssociatedKeys.clearButton,
                             button,
                             .OBJC_ASSOCIATION_RETAIN_NONATOMIC)
    return button
  }
  
  private func createClearButton() -> UIButton {
    let button = UIButton(type: .custom)
    
    if #available(iOS 15.0, *) {
      var config = UIButton.Configuration.plain()
      // Make the button square and let Auto Layout size it via constraints later
      config.contentInsets = NSDirectionalEdgeInsets(
        top: Constants.imageInset,
        leading: Constants.imageInset,
        bottom: Constants.imageInset,
        trailing: Constants.imageInset
      )
      config.image = Constants.clearImage
      config.baseForegroundColor = UIColor(named: "clr_fieldworkGreen") ?? .systemGreen
      // Keep aspect fit-like appearance
      config.preferredSymbolConfigurationForImage = UIImage.SymbolConfiguration(scale: .medium)
      button.configuration = config
      // Ensure template rendering uses tintColor
      button.tintColor = UIColor(named: "clr_fieldworkGreen") ?? .systemGreen
    } else {
      button.setImage(Constants.clearImage, for: .normal)
      button.imageView?.tintColor = UIColor(named: "clr_fieldworkGreen") ?? .systemGreen
      // Deprecated on iOS 15+, but still valid before that
      button.imageEdgeInsets = UIEdgeInsets(top: Constants.imageInset,
                                            left: Constants.imageInset,
                                            bottom: Constants.imageInset,
                                            right: Constants.imageInset)
      button.contentMode = .scaleAspectFit
      button.tintColor = UIColor(named: "clr_fieldworkGreen") ?? .systemGreen
    }
    
    button.addTarget(self, action: #selector(clearButtonTap), for: .touchUpInside)
    return button
  }
  
  private func setClearButtonHidden(_ isHidden: Bool) {
    let constraints: [NSLayoutConstraint] = [
      fw_clearButton.centerYAnchor.constraint(equalTo: contentView.centerYAnchor),
      fw_clearButton.trailingAnchor.constraint(equalTo: contentView.trailingAnchor),
      fw_clearButton.widthAnchor.constraint(equalToConstant: Constants.sideMeasure),
      fw_clearButton.heightAnchor.constraint(equalToConstant: Constants.sideMeasure)
    ]
    fw_clearButton.translatesAutoresizingMaskIntoConstraints = false
    
    if isHidden {
      fw_clearButton.removeFromSuperview()
      NSLayoutConstraint.deactivate(constraints)
    } else {
      if fw_clearButton.superview == nil {
        contentView.addSubview(fw_clearButton)
        NSLayoutConstraint.activate(constraints)
      }
    }
  }
  
  @objc private func clearButtonTap() { fw_onClearButtonTap?() }
}