Perform animation

AnimationForExpandableButton.swift

 fileprivate func performAnimation() {
        let screenSize = UIScreen.main.bounds
        
        let stackedButtons = self.buttonStackView.arrangedSubviews
        
        let animation = UIViewPropertyAnimator(duration: 0.3, curve: .easeOut) {
            
            //hide or show the stackview.
            self.buttonStackView.isHidden = self.buttonsAreHidden
            
            /// change button image and update the width constraint
            self.updateButtonImage = !self.buttonsAreHidden
            self.widthConstant = self.buttonsAreHidden ?  self.priceButton.frame.width : screenSize.size.width - 20
            
            //handle left borders while animating.
            stackedButtons.forEach({ (button) in
                button.layer.sublayers?.first?.isHidden = self.buttonsAreHidden
            })
            
            //remove all existing constraints
            self.backgroundView.constraints.forEach({ (constraint) in
                constraint.isActive = false
            })
            
            self.view.layoutIfNeeded()
        }
        animation.startAnimation()
    }