A protocol that enables wiggle-wiggle motion to UICollectionViewCells

SwiftCellProtocol.swift

//MARK:- UICollectionViewCells
import Material

public protocol CellEditable {

    func deleteElement()
    func startBeingAfraid()
    func stopBeingAfraid()
}

public extension CellEditable where Self: UICollectionViewCell {

    //
    // I can't make this button work. addTarget doesn't bind correctly and never gets fired when I tap it.
    //
    var removeButton: Button? {
        get {
            let tag = 666
            if let removeButton = self.contentView.viewWithTag(tag) as? Button {
                return removeButton
            } else {
                let removeButton = Button(frame: CGRect(x: 10, y: 10, width: 25, height: 25))
                removeButton.isUserInteractionEnabled = true
                removeButton.translatesAutoresizingMaskIntoConstraints = false
                removeButton.layer.cornerRadius = (removeButton.frame.size.width / 2.0) as CGFloat
                removeButton.clipsToBounds = true
                removeButton.backgroundColor = SQThemeManager.currentTheme().color.accentDark
                removeButton.tag = tag
                removeButton.setImage(Icon.close, for: .normal)
                removeButton.tintColor = .white
                return removeButton
            }
        }
    }


    /// Makes the cell frame wiggle
    func startBeingAfraid() {

        let angleLeft = CGFloat((-5.0 * Double.pi) / 180.0)
        let angleRight = CGFloat((5.0 * Double.pi) / 180.0)

        if let rmButton = self.removeButton {
            self.addSubview(rmButton)

            NSLayoutConstraint.activate([rmButton.topAnchor.constraint(equalTo: self.topAnchor),
                                         rmButton.leadingAnchor.constraint(equalTo: self.leadingAnchor),
                                         rmButton.widthAnchor.constraint(equalToConstant: 25),
                                         rmButton.heightAnchor.constraint(equalToConstant: 25)])

        }

        self.contentView.transform = CGAffineTransform(rotationAngle: angleLeft)

        UIView.animate(withDuration: 0.15,
                       delay: 0,
                       options: [.allowUserInteraction, .autoreverse, .repeat],
                       animations: {
                        self.contentView.transform = CGAffineTransform(rotationAngle: angleRight)
        }, completion: nil)
    }


    /// Stops the cell frame to wiggle
    func stopBeingAfraid() {
    
        UIView.animate(withDuration: 0.15,
                       delay: 0,
                       options: [.allowUserInteraction, .beginFromCurrentState, .curveEaseOut],
                       animations: {
                        self.contentView.transform = CGAffineTransform.identity
        }, completion: nil)

        if let rmButton = self.removeButton {
            self.removeConstraints(rmButton.constraints)
            self.removeButton?.removeFromSuperview()
            self.setNeedsLayout()
            self.layoutIfNeeded()
        }
    }
}