Swipeable UITableViewCell where you can use custom view behind cell.contentView

SwipeableCell.swift

//
//  SwipeableCell.swift
//  Antony Alkmim
//
//  Created by Antony Alkmim on 09/07/18.
// Inspired by: https://www.raywenderlich.com/62435/make-swipeable-table-view-cell-actions-without-going-nuts-scroll-views
//

import UIKit
import PINRemoteImage

class SwipeableCell: UITableViewCell {

    @IBOutlet weak var wrapperView: UIView!
    
    @IBOutlet weak var menuView: UIView!
    @IBOutlet weak var unreadButton: UIButton!
    @IBOutlet weak var deleteButton: UIButton!
    
    @IBOutlet weak var leftConstraint: NSLayoutConstraint!
    @IBOutlet weak var rightConstraint: NSLayoutConstraint!
    
    private var panStartPoint: CGPoint!
    private var startingRightLayoutConstraintConstant: CGFloat = 0
    private let buttonTotalWidth: CGFloat = 218.0
    
    private var isMenuOpened = false
    
    override func awakeFromNib() {
        super.awakeFromNib()
        
        selectionStyle = .none
        
        // swipe gesture to show menu options
        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(panThisCell(_:)))
        panGesture.delegate = self
        wrapperView.isUserInteractionEnabled = true
        wrapperView.addGestureRecognizer(panGesture)
    }

    override func prepareForReuse() {
        super.prepareForReuse()
        hideOptionsButtons()
    }
    
    override func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return true // this enables tableview scroll
    }
    
    private func hideOptionsButtons() {
        if startingRightLayoutConstraintConstant == 0 && rightConstraint.constant == 0 {
            //Already all the way closed, no bounce necessary
            return
        }
        
        rightConstraint.constant = 0
        leftConstraint.constant = 0
        startingRightLayoutConstraintConstant = rightConstraint.constant
        isMenuOpened = false
        updateConstraintsIfNeeded()
    }
    
    private func showOptionsButtons() {
        if startingRightLayoutConstraintConstant == buttonTotalWidth && rightConstraint.constant == buttonTotalWidth {
            return
        }
        
        leftConstraint.constant = -buttonTotalWidth //- kBounceValue
        rightConstraint.constant = buttonTotalWidth //+ kBounceValue
        startingRightLayoutConstraintConstant = rightConstraint.constant
        isMenuOpened = true
        updateConstraintsIfNeeded()
        
    }
    
    override func updateConstraintsIfNeeded() {
        super.updateConstraintsIfNeeded()
        UIView.animate(withDuration: 0.2, delay: 0, options: .curveEaseOut, animations: {
            self.layoutIfNeeded()
        })
    }
    
    private func panRecognizeChanged(_ currentPoint: CGPoint) {
        let deltaX = currentPoint.x - panStartPoint.x
        
        let panningLeft = currentPoint.x < panStartPoint.x
        
        if startingRightLayoutConstraintConstant == 0 {
            //The cell was closed and is now opening
            if !panningLeft {
                let constant = max(-deltaX, 0)
                if constant == 0 {
                    hideOptionsButtons()
                } else {
                    self.rightConstraint.constant = -constant
                }
            } else {
                let constant = min(-deltaX, buttonTotalWidth)
                if constant == buttonTotalWidth {
                    showOptionsButtons()
                } else {
                    self.rightConstraint.constant = constant
                }
            }
        } else {
            //The cell was at least partially open.
            let adjustment = startingRightLayoutConstraintConstant - deltaX
            if !panningLeft {
                let constant = max(adjustment, 0)
                if constant == 0 {
                    hideOptionsButtons()
                } else {
                    rightConstraint.constant = constant
                }
            } else {
                let constant = min(adjustment, buttonTotalWidth)
                if constant == buttonTotalWidth {
                    showOptionsButtons()
                } else {
                    rightConstraint.constant = constant
                }
            }
        }
        
        leftConstraint.constant = -rightConstraint.constant
    }
    
    private func panRecognizeEnded() {
        if startingRightLayoutConstraintConstant == 0 {
            //Cell was opening
            let halfOfButtonOne: CGFloat = 107 //button1.frame.width / 2
            if rightConstraint.constant >= halfOfButtonOne {
                //Open all the way
                showOptionsButtons()
            } else {
                //Re-close
                hideOptionsButtons()
            }
        } else {
            //Cell was closing
            let buttonOnePlusHalfOfButton2: CGFloat = 107 + (107/2)//self.button1.frame.width + (self.button2.frame.width / 2)
            if rightConstraint.constant >= buttonOnePlusHalfOfButton2 {
                //Re-open all the way
                showOptionsButtons()
            } else {
                //Close
                hideOptionsButtons()
            }
        }
    }
    
    @objc private func panThisCell(_ recognizer: UIPanGestureRecognizer) {
        switch recognizer.state {
        case .began:
            panStartPoint = recognizer.translation(in: wrapperView)
        case .changed:
            let currPoint = recognizer.translation(in: wrapperView)
            panRecognizeChanged(currPoint)
        case .ended:
            panRecognizeEnded()
        case .cancelled:
            if startingRightLayoutConstraintConstant == 0 { //Cell was closed - reset everything to 0
                hideOptionsButtons()
            } else { //Cell was open - reset to the open state
                showOptionsButtons()
            }
        default: break
        }
    }
    
    override func setSelected(_ selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)
        if isMenuOpened {
            hideOptionsButtons()
        }
    }
    
}