//
//  ViewController.swift
//  ColorScroll
//
//  Created by Michael Nino Evensen on 25/09/2019.
//  Copyright © 2019 Michael Nino Evensen. All rights reserved.
//

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var colorView: UIView!
    var animator: UIViewPropertyAnimator!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Initial Color
        colorView.backgroundColor = .red

        // Setup animation
        self.animator = UIViewPropertyAnimator(duration: 1.0, curve: .easeOut) { [unowned self] in
            self.colorView.backgroundColor = .green
        }
    }
}

extension ViewController: UIScrollViewDelegate {
    func scrollViewDidScroll(_ scrollView: UIScrollView) {

        let delta = min(max(0, scrollView.contentOffset.y / self.view.frame.size.height), 1)
        self.animator.fractionComplete = delta
    }
}