InteractiveMenu4.swift

// MARK: Show / Hide
extension InteractiveMenu {
    @objc fileprivate func blurViewDidTapped() {
        self.hideView()
    }
    
   
    
    @objc fileprivate func containerViewPanned(recognizer: UIPanGestureRecognizer) {
        switch recognizer.state {
        
        case .began:
            self.animator.stopAnimation(false) //1
        
        case .changed:
            let currentTranslation = recognizer.translation(in: recognizer.view!)
            self.setContainerViewCenter(currentTranslation: currentTranslation)
            self.setBlurViewAlpha()
            recognizer.setTranslation(CGPoint.zero, in: recognizer.view!)
            
            
        case .ended , .cancelled:
            let velocity = recognizer.velocity(in: recognizer.view!).y //2
            let distance = self.distanceForVelocity(velocity: velocity)
            var prefferedVelocity = velocity / distance
            if prefferedVelocity < 0 { prefferedVelocity = max(-30 , prefferedVelocity) }
            let diffOpenYPos:CGFloat = abs(recognizer.view!.frame.origin.y - self.frameOpenPosition.origin.y)
            let diffCloseYPos:CGFloat = abs(recognizer.view!.frame.origin.y - self.frameClosedPosition.origin.y)
           
            let velocityTreshold:CGFloat = 0.5 //3
            if abs(prefferedVelocity) <= velocityTreshold && diffOpenYPos <= diffCloseYPos {
                self.showView()
            }
            else if abs(prefferedVelocity) <= velocityTreshold && diffOpenYPos > diffCloseYPos {
                self.hideView()
            }
            else if abs(prefferedVelocity) > velocityTreshold && prefferedVelocity < 0 {
                let velocityValue = velocity * 0.01
                self.showView(initialVelocity: velocityValue)
            }
            else if abs(prefferedVelocity) > velocityTreshold && prefferedVelocity >= 0 {
                let velocityValue = velocity * 0.01
                self.hideView(initialVelocity: velocityValue)
            }
            else {
                self.showView()
            }

        default: break
        }
    }
    
    
    //4
    private func applyRubberBandingIfNeeded(currentTranslation: CGPoint)->Bool {
           let yPosNext =  self.containerView.center.y + currentTranslation.y
           let openedCenterYPos:CGFloat = self.frameOpenPosition.origin.y + self.frameOpenPosition.size.height / 2
           let closedCenterYPos:CGFloat = self.frameClosedPosition.origin.y + self.frameClosedPosition.size.height / 2
           guard yPosNext < openedCenterYPos || yPosNext > closedCenterYPos else { return false }
           let translationY = currentTranslation.y * 0.05
           self.containerView.center = CGPoint(x: self.containerView.center.x, y: self.containerView.center.y + translationY)
           return true
       }
       
       
       private func setContainerViewCenter(currentTranslation: CGPoint) {
           guard self.applyRubberBandingIfNeeded(currentTranslation: currentTranslation) else {
               self.containerView.center = CGPoint(x: self.containerView.center.x, y: self.containerView.center.y + currentTranslation.y)
               return
           }
       }
       
       private func setBlurViewAlpha() {
           let openPosDistance:CGFloat = self.containerView.frame.origin.y - self.frameOpenPosition.origin.y
           let maxDistance:CGFloat = self.frameClosedPosition.origin.y - self.frameOpenPosition.origin.y
           let rateOpened:CGFloat = openPosDistance / maxDistance
           let blurViewAlpha:CGFloat = min(0.7, 1-rateOpened)
           self.viewBlurBackground.alpha = blurViewAlpha
       }
     
      //5
     private func distanceForVelocity(velocity:CGFloat)->CGFloat {
        let openedCenterYPos:CGFloat = self.frameOpenPosition.origin.y + self.frameOpenPosition.size.height / 2
        let closedCenterYPos:CGFloat = self.frameClosedPosition.origin.y + self.frameClosedPosition.size.height / 2
        if velocity < 0 { return abs(openedCenterYPos - self.containerView.center.y) }
        return abs(closedCenterYPos - self.containerView.center.y)
    }
    
    fileprivate func showView(initialVelocity: CGFloat = 0 ) {
         if self.animator.isRunning { self.animator.stopAnimation(true) }
        self.frame = CGRect(x: self.frame.origin.x, y: 0, width: self.frame.size.width, height: self.frame.size.height)
        self.viewBlurBackground.alpha = 0.7
        //6
        let timingParameters =  UISpringTimingParameters(damping: self.dampingValue, response: self.responseValue , initialVelocity: CGVector(dx: initialVelocity, dy: initialVelocity))
        self.animator = UIViewPropertyAnimator(duration: 0, timingParameters: timingParameters )
        self.animator.addAnimations {
            self.containerView.frame = self.frameOpenPosition
        }
        self.animator.addCompletion { pos in
            guard pos == .end else { return }
            // fire delegate
        }
        
        self.animator.startAnimation()
    }
    
    fileprivate func hideView(initialVelocity: CGFloat = 0) {
        if self.animator.isRunning { self.animator.stopAnimation(true) }
        print("Velocity : \(initialVelocity)")
        let timingParameters =  UISpringTimingParameters(damping: self.dampingValue, response: self.responseValue , initialVelocity: CGVector(dx: initialVelocity, dy: initialVelocity))
        self.animator = UIViewPropertyAnimator(duration: 0, timingParameters: timingParameters )
        self.animator.addAnimations {
            self.containerView.frame = self.frameClosedPosition
            self.viewBlurBackground.alpha = 0
        }
        
        self.animator.addCompletion { pos in
            guard pos == .end else { return }
            self.frame = CGRect(x: self.frame.origin.x, y: self.frame.size.height, width: self.frame.size.width, height: self.frame.size.height)
            // fire delegate
        }
        
        self.animator.startAnimation()
    }
    
}