import UIKit

class ViewController: UIViewController, UIScrollViewDelegate, UIGestureRecognizerDelegate {

    @IBOutlet weak var scrollView: UIScrollView!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        self.scrollView.delegate = self

        let swipeUp = UISwipeGestureRecognizer(target: self, action: #selector(ViewController.respondToSwipeGesture(gesture:)))
        swipeUp.direction = UISwipeGestureRecognizerDirection.up
        let swipeDown = UISwipeGestureRecognizer(target: self, action: #selector(ViewController.respondToSwipeGesture(gesture:)))
        swipeDown.direction = UISwipeGestureRecognizerDirection.down

        self.view.addGestureRecognizer(swipeUp)
        self.view.addGestureRecognizer(swipeDown)
    }

    // here are those protocol methods with Swift syntax
    public func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return true
    }

    public func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldReceive touch: UITouch) -> Bool {
        return true
    }

    // Debugging - All Swipes Are Detected Now
    func respondToSwipeGesture(gesture: UIGestureRecognizer) {
        if let swipeGesture = gesture as? UISwipeGestureRecognizer {
            switch swipeGesture.direction {
            case UISwipeGestureRecognizerDirection.down:
                print("Swiped down")
            case UISwipeGestureRecognizerDirection.up:
                print("Swiped up")
            default:
                break
            }
        }
    }

    override func viewDidAppear(_ animated: Bool) {
        scrollView.contentSize.height = 1000
        self.view.layoutIfNeeded()
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

}