```
import UIKit

class BBPMainController: UIViewController, UIScrollViewDelegate {
	
	var scrollView: UIScrollView!
	
	var applocationScrollOverlayerAboveView: UIView!
	var applocationScrollOverlayerBelowView: UIView!
	
	var sectorsController: BBPSectorsController!
	var welcomeController: BBPWelcomeController!
  var caseController: BBPCaseController!
	var applicationController: BBPApplicationController!
   
  var wrController: BBPWrController!
   
	override func viewDidLoad() {
		super.viewDidLoad()
		
		// Set background
		
		view.backgroundColor = UIColor.bird.slate
		
		// Create UI
		
		// Scroll View
		
		scrollView = UIScrollView()
		scrollView.translatesAutoresizingMaskIntoConstraints = false
		scrollView.isPagingEnabled = true
		scrollView.showsVerticalScrollIndicator = false
		scrollView.delegate = self
		view.insertSubview(scrollView, at: 0)
		
		view.addConstraint(NSLayoutConstraint(item: scrollView, attribute: .left, relatedBy: .equal, toItem: view, attribute: .left, multiplier: 1, constant: 0))
		view.addConstraint(NSLayoutConstraint(item: scrollView, attribute: .right, relatedBy: .equal, toItem: view, attribute: .right, multiplier: 1, constant: 0))
		
		view.addConstraint(NSLayoutConstraint(item: scrollView, attribute: .top, relatedBy: .equal, toItem: view, attribute: .top, multiplier: 1, constant: 0))
		view.addConstraint(NSLayoutConstraint(item: scrollView, attribute: .bottom, relatedBy: .equal, toItem: view, attribute: .bottom, multiplier: 1, constant: 0))
		
		// Page 0 (Post application above) - Overlayer 1
		
		applocationScrollOverlayerAboveView = UIView()
		applocationScrollOverlayerAboveView.translatesAutoresizingMaskIntoConstraints = false
		applocationScrollOverlayerAboveView.backgroundColor = UIColor.black
		scrollView.addSubview(applocationScrollOverlayerAboveView)
		
		scrollView.addConstraint(NSLayoutConstraint(item: applocationScrollOverlayerAboveView, attribute: .left, relatedBy: .equal, toItem: scrollView, attribute: .left, multiplier: 1, constant: 0))
		scrollView.addConstraint(NSLayoutConstraint(item: applocationScrollOverlayerAboveView, attribute: .right, relatedBy: .equal, toItem: scrollView, attribute: .right, multiplier: 1, constant: 0))
		
		scrollView.addConstraint(NSLayoutConstraint(item: applocationScrollOverlayerAboveView, attribute: .top, relatedBy: .equal, toItem: scrollView, attribute: .top, multiplier: 1, constant: 0))
		
		scrollView.addConstraint(NSLayoutConstraint(item: applocationScrollOverlayerAboveView, attribute: .width, relatedBy: .equal, toItem: scrollView, attribute: .width, multiplier: 1, constant: 0))
		scrollView.addConstraint(NSLayoutConstraint(item: applocationScrollOverlayerAboveView, attribute: .height, relatedBy: .equal, toItem: scrollView, attribute: .height, multiplier: 1, constant: 0))
		
		
     
    // Page 1.5 (Sectors)
     
    caseController = storyboard!.instantiateViewController(withIdentifier: "Case") as! BBPCaseController
    caseController.view.translatesAutoresizingMaskIntoConstraints = false
    scrollView.addSubview(caseController.view)
    addChild(caseController)
     
    scrollView.addConstraint(NSLayoutConstraint(item: caseController.view, attribute: .left, relatedBy: .equal, toItem: scrollView, attribute: .left, multiplier: 1, constant: 0))
    scrollView.addConstraint(NSLayoutConstraint(item: caseController.view, attribute: .right, relatedBy: .equal, toItem: scrollView, attribute: .right, multiplier: 1, constant: 0))
     
    scrollView.addConstraint(NSLayoutConstraint(item: caseController.view, attribute: .top, relatedBy: .equal, toItem: applocationScrollOverlayerAboveView, attribute: .bottom, multiplier: 1, constant: 0))
     
    scrollView.addConstraint(NSLayoutConstraint(item: caseController.view, attribute: .width, relatedBy: .equal, toItem: scrollView, attribute: .width, multiplier: 1, constant: 0))
    scrollView.addConstraint(NSLayoutConstraint(item: caseController.view, attribute: .height, relatedBy: .equal, toItem: scrollView, attribute: .height, multiplier: 1, constant: 0))
     
		// Page 2 (Welcome)
		
		welcomeController = storyboard!.instantiateViewController(withIdentifier: "Welcome") as! BBPWelcomeController
		welcomeController.view.translatesAutoresizingMaskIntoConstraints = false
		scrollView.addSubview(welcomeController.view)
		addChild(caseController)
		
		scrollView.addConstraint(NSLayoutConstraint(item: welcomeController.view, attribute: .left, relatedBy: .equal, toItem: scrollView, attribute: .left, multiplier: 1, constant: 0))
		scrollView.addConstraint(NSLayoutConstraint(item: welcomeController.view, attribute: .right, relatedBy: .equal, toItem: scrollView, attribute: .right, multiplier: 1, constant: 0))
		
		scrollView.addConstraint(NSLayoutConstraint(item: welcomeController.view, attribute: .top, relatedBy: .equal, toItem: caseController.view, attribute: .bottom, multiplier: 1, constant: 0))
		
		scrollView.addConstraint(NSLayoutConstraint(item: welcomeController.view, attribute: .width, relatedBy: .equal, toItem: scrollView, attribute: .width, multiplier: 1, constant: 0))
		scrollView.addConstraint(NSLayoutConstraint(item: welcomeController.view, attribute: .height, relatedBy: .equal, toItem: scrollView, attribute: .height, multiplier: 1, constant: 0))
     
     
		// Page 3 (Post application) - Overlayer 2
		
		applocationScrollOverlayerBelowView = UIView()
		applocationScrollOverlayerBelowView.translatesAutoresizingMaskIntoConstraints = false
		applocationScrollOverlayerBelowView.backgroundColor = UIColor.black
		scrollView.addSubview(applocationScrollOverlayerBelowView)
		
		scrollView.addConstraint(NSLayoutConstraint(item: applocationScrollOverlayerBelowView, attribute: .left, relatedBy: .equal, toItem: scrollView, attribute: .left, multiplier: 1, constant: 0))
		scrollView.addConstraint(NSLayoutConstraint(item: applocationScrollOverlayerBelowView, attribute: .right, relatedBy: .equal, toItem: scrollView, attribute: .right, multiplier: 1, constant: 0))
		
		scrollView.addConstraint(NSLayoutConstraint(item: applocationScrollOverlayerBelowView, attribute: .top, relatedBy: .equal, toItem: welcomeController.view, attribute: .bottom, multiplier: 1, constant: 0))
		scrollView.addConstraint(NSLayoutConstraint(item: applocationScrollOverlayerBelowView, attribute: .bottom, relatedBy: .equal, toItem: scrollView, attribute: .bottom, multiplier: 1, constant: 0))
		
		scrollView.addConstraint(NSLayoutConstraint(item: applocationScrollOverlayerBelowView, attribute: .width, relatedBy: .equal, toItem: scrollView, attribute: .width, multiplier: 1, constant: 0))
		scrollView.addConstraint(NSLayoutConstraint(item: applocationScrollOverlayerBelowView, attribute: .height, relatedBy: .equal, toItem: scrollView, attribute: .height, multiplier: 1, constant: 0))
		
		// Page 3 (Post application) - Controller
		
		applicationController = storyboard!.instantiateViewController(withIdentifier: "PostApplication") as! BBPApplicationController
		applicationController.mainController = self
		applicationController.view.translatesAutoresizingMaskIntoConstraints = false
		view.insertSubview(applicationController.view, belowSubview: scrollView)
		addChild(applicationController)
		
		view.addConstraint(NSLayoutConstraint(item: applicationController.view, attribute: .left, relatedBy: .equal, toItem: view, attribute: .left, multiplier: 1, constant: 0))
		view.addConstraint(NSLayoutConstraint(item: applicationController.view, attribute: .right, relatedBy: .equal, toItem: view, attribute: .right, multiplier: 1, constant: 0))
		
		view.addConstraint(NSLayoutConstraint(item: applicationController.view, attribute: .top, relatedBy: .equal, toItem: view, attribute: .top, multiplier: 1, constant: 0))
		view.addConstraint(NSLayoutConstraint(item: applicationController.view, attribute: .bottom, relatedBy: .equal, toItem: view, attribute: .bottom, multiplier: 1, constant: 0))
	}
	
	var firstView = true
	
	override func viewDidAppear(_ animated: Bool) {
		super.viewDidAppear(animated)
		
		// Scroll to default
		
		if firstView {
			firstView = false
			
			scrollView.contentOffset = CGPoint(x: 0, y: view.bounds.height * 2)
		}
	}
	
	// MARK: - Status bar
	
	override var prefersStatusBarHidden : Bool {
		return true
	}
	
	// MARK: - Scrolling
	
	func scrollViewDidScroll(_ scrollView: UIScrollView) {
		
		// -- Update overlayer alpha value --
		
		let maxAlphaValue: CGFloat = 0.75
		
		// Calcuate alpha
		
		let aboveAlpha = 0 - (maxAlphaValue - maxAlphaValue * ((scrollView.contentOffset.y - view.bounds.height) / view.bounds.height)) + maxAlphaValue * 2
		let belowAlpha = maxAlphaValue - maxAlphaValue * ((scrollView.contentOffset.y - view.bounds.height) / view.bounds.height) + maxAlphaValue
		
		// Set alpha or 0 if alpha is greater than 1
		
		applocationScrollOverlayerAboveView.alpha = aboveAlpha > 1 ? 0 : max(0, min(1, aboveAlpha))
		applocationScrollOverlayerBelowView.alpha = belowAlpha > 1 ? 0 : max(0, min(1, belowAlpha))
		
		// -- Update transform scale and view alpha value --
		
		let minScaleValue: CGFloat = 0.6
		let scale: CGFloat
		
		if aboveAlpha > 1 {
			scale = ((scrollView.contentOffset.y - view.bounds.height * 2) / view.bounds.height) * minScaleValue + abs(minScaleValue - 1)
		} else {
			scale = 0 - ((scrollView.contentOffset.y - view.bounds.height) / view.bounds.height) * minScaleValue + abs(minScaleValue - 1)
		}
		
		applicationController.view.transform = CGAffineTransform(scaleX: scale, y: scale)
		applicationController.view.alpha = max(0, min(1, scale))
	}
	
	func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
		userDidCompleteScrollDrag()
	}
	
	func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
		if !decelerate {
			userDidCompleteScrollDrag()
		}
	}
	
	var prevScrollPositionWasAbove = false
	
	func userDidCompleteScrollDrag() {
		
		let atSectors = scrollView.contentOffset.y == view.bounds.height
		let atApplicationAbove = scrollView.contentOffset.y <= 0
		let atApplicationBelow = scrollView.contentOffset.y >= view.bounds.height * 3
		
		// Hide scrollview if application view is on top
		
		if atApplicationAbove || atApplicationBelow {
			scrollView.isHidden = true
			
			prevScrollPositionWasAbove = atApplicationAbove
			
			applicationController.viewDidBecomeFirst()
		}
			
			// Start intro movie if at sectors view
			
		else if atSectors {
			//caseController.playIntroMovie()
		}
			
			// Must be welcome view
		
		else {
			//sectorsController.resetIntroMovieView()
		}
	}
	
	// MARK: - Scrolling
	
	func scrollToDefault(delay: TimeInterval = 0) {
		scrollView.isHidden = false
		
		UIView.setAnimationsEnabled(true) // When is animations disabled ??
		
		UIView.animate(withDuration: 0.3, delay: delay, options: [], animations: {
			self.scrollView.contentOffset = CGPoint(x: 0, y: self.view.bounds.height * (self.prevScrollPositionWasAbove ? 1 : 2))
		}, completion: nil)
	}
	
	var applicationControllerVisible: Bool {
		return scrollView.contentOffset.y <= 0 || scrollView.contentOffset.y >= view.bounds.height * 3
	}
}
```