Distance travelled after decelerating to zero velocity at a constant rate. The included Playground file shows how you can use it with a pan gesture as an example.

CGPoint+Target.swift

public extension CGPoint {

    // The target points after decelerating to 0 velocity at a constant rate
    func target(initialVelocity: CGPoint, decelerationRate: CGFloat = UIScrollView.DecelerationRate.normal.rawValue) -> CGPoint {
        let x = self.x + self.x.target(initialVelocity: initialVelocity.x, decelerationRate: decelerationRate)
        let y = self.y + self.y.target(initialVelocity: initialVelocity.y, decelerationRate: decelerationRate)
        return CGPoint(x: x, y: y)
    }

}

fileprivate extension CGFloat {

    func target(initialVelocity: CGFloat, decelerationRate: CGFloat = UIScrollView.DecelerationRate.normal.rawValue) -> CGFloat {
        return (initialVelocity / 1000.0) * decelerationRate / (1.0 - decelerationRate)
    }

}

Deceleration Playground.swift

//: A UIKit based Playground for presenting user interface
  
import UIKit
import PlaygroundSupport

final class ViewController: UIViewController {

    private var gesture: UIPanGestureRecognizer!
    private let box = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)

        let gesture = UIPanGestureRecognizer(target: self, action: #selector(handlePan(gesture:)))
        box.addGestureRecognizer(gesture)

        box.center = view.center
        box.layer.cornerRadius = 8
        box.backgroundColor = .red

        view.addSubview(box)
        view.backgroundColor = .white
    }

    @objc private func handlePan(gesture: UIPanGestureRecognizer) {
        let translation = gesture.translation(in: gesture.view)

        switch gesture.state {
        case .began, .changed:
            box.center.x += translation.x
            box.center.y += translation.y
        case .ended:
            let velocity = gesture.velocity(in: gesture.view)
            let target = translation.target(initialVelocity: velocity)

            UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.9, initialSpringVelocity: 1, options: [], animations: {
                self.box.center.x += target.x
                self.box.center.y += target.y
            }, completion: nil)
        default: break
        }

        gesture.setTranslation(.zero, in: gesture.view)
    }

}

PlaygroundPage.current.liveView = ViewController()