guidelines - En iOS, ¿cómo arrastrar hacia abajo para descartar un modal?

select ios

Question

Una forma común de descartar un modal es deslizar hacia abajo: ¿cómo le permitimos al usuario arrastrar el modal hacia abajo, si está lo suficientemente lejos, el modal se descarta, de lo contrario, vuelve a la posición original?

Por ejemplo, podemos encontrar esto usado en las vistas de fotos de la aplicación de Twitter o en el modo "descubrir" de Snapchat.

Subprocesos similares indican que podemos usar un UISwipeGestureRecognizer y [self-sheedViewControllerAnimated ...] para descartar un VC modal cuando un usuario desliza hacia abajo. Pero esto solo maneja un solo deslizamiento, no permitiendo que el usuario arrastre el modal.

Answer 1

Acabo de crear un tutorial para arrastrar interactivamente un modal para descartarlo.

http://www.thorntech.com/2016/02/ios-tutorial-close-modal-dragging/

Al principio, encontré que este tema era confuso, por lo que el tutorial lo desarrolla paso a paso.

Si solo desea ejecutar el código usted mismo, este es el repositorio:

github.com/ThornTechPublic/InteractiveModal

Este es el enfoque que utilicé:

Ver controlador

Anula la animación de descarte con una personalizada. Si el usuario arrastra el modal, el interactor activa.

import UIKit

class ViewController: UIViewController {
    let interactor = Interactor()
    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if let destinationViewController = segue.destinationViewController as? ModalViewController {
            destinationViewController.transitioningDelegate = self
            destinationViewController.interactor = interactor
        }
    }
}

extension ViewController: UIViewControllerTransitioningDelegate {
    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return DismissAnimator()
    }
    func interactionControllerForDismissal(animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
        return interactor.hasStarted ? interactor : nil
    }
}

Despedir animador

Creas un animador personalizado. Esta es una animación personalizada que empaqueta dentro de un protocolo UIViewControllerAnimatedTransitioning .

import UIKit

class DismissAnimator : NSObject {
}

extension DismissAnimator : UIViewControllerAnimatedTransitioning {
    func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
        return 0.6
    }

    func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
        guard
            let fromVC = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey),
            let toVC = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey),
            let containerView = transitionContext.containerView()
            else {
                return
        }
        containerView.insertSubview(toVC.view, belowSubview: fromVC.view)
        let screenBounds = UIScreen.mainScreen().bounds
        let bottomLeftCorner = CGPoint(x: 0, y: screenBounds.height)
        let finalFrame = CGRect(origin: bottomLeftCorner, size: screenBounds.size)

        UIView.animateWithDuration(
            transitionDuration(transitionContext),
            animations: {
                fromVC.view.frame = finalFrame
            },
            completion: { _ in
                transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
            }
        )
    }
}

Interactor

Subclase UIPercentDrivenInteractiveTransition para que pueda actuar como su máquina de estados. Dado que ambas VC acceden al objeto interactor, úselo para realizar un seguimiento del progreso de la panorámica.

import UIKit

class Interactor: UIPercentDrivenInteractiveTransition {
    var hasStarted = false
    var shouldFinish = false
}

Controlador de vista modal

Esto asigna el estado de gesto panorámico a las llamadas al método interactor. El valor de translationInView() y determina si el usuario cruzó un umbral. Cuando se .Ended gesto de .Ended , el interactor finaliza o se cancela.

import UIKit

class ModalViewController: UIViewController {

    var interactor:Interactor? = nil

    @IBAction func close(sender: UIButton) {
        dismissViewControllerAnimated(true, completion: nil)
    }

    @IBAction func handleGesture(sender: UIPanGestureRecognizer) {
        let percentThreshold:CGFloat = 0.3

        // convert y-position to downward pull progress (percentage)
        let translation = sender.translationInView(view)
        let verticalMovement = translation.y / view.bounds.height
        let downwardMovement = fmaxf(Float(verticalMovement), 0.0)
        let downwardMovementPercent = fminf(downwardMovement, 1.0)
        let progress = CGFloat(downwardMovementPercent)
        guard let interactor = interactor else { return }

        switch sender.state {
        case .Began:
            interactor.hasStarted = true
            dismissViewControllerAnimated(true, completion: nil)
        case .Changed:
            interactor.shouldFinish = progress > percentThreshold
            interactor.updateInteractiveTransition(progress)
        case .Cancelled:
            interactor.hasStarted = false
            interactor.cancelInteractiveTransition()
        case .Ended:
            interactor.hasStarted = false
            interactor.shouldFinish
                ? interactor.finishInteractiveTransition()
                : interactor.cancelInteractiveTransition()
        default:
            break
        }
    }

}

Answer 2

Actualiza masivamente el repositorio para Swift 4 .

Para Swift 3 , he creado lo siguiente para presentar un UIViewController de derecha a izquierda y descartarlo mediante un gesto panorámico. He subido esto como un repositorio de GitHub .

Archivo DismissOnPanGesture.swift :

import UIKit

class VC1: UIViewController, UIViewControllerTransitioningDelegate {

    let interactor = Interactor()

    @IBAction func present(_ sender: Any) {
        let vc = self.storyboard?.instantiateViewController(withIdentifier: "VC2") as! VC2
        vc.transitioningDelegate = self
        vc.interactor = interactor

        presentVCRightToLeft(self, vc)
    }

    func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        return DismissAnimator()
    }

    func interactionControllerForDismissal(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
        return interactor.hasStarted ? interactor : nil
    }
}

class VC2: UIViewController {

    var interactor:Interactor? = nil

    override func viewDidLoad() {
        super.viewDidLoad()
        instantiatePanGestureRecognizer(self, #selector(gesture))
    }

    @IBAction func dismiss(_ sender: Any) {
        dismissVCLeftToRight(self)
    }

    func gesture(_ sender: UIScreenEdgePanGestureRecognizer) {
        dismissVCOnPanGesture(self, sender, interactor!)
    }
}

Uso fácil:

func panGestureAction(_ panGesture: UIPanGestureRecognizer) {
    let translation = panGesture.translation(in: view)

    if panGesture.state == .began {
        originalPosition = view.center
        currentPositionTouched = panGesture.location(in: view)    
    } else if panGesture.state == .changed {
        view.frame.origin = CGPoint(
            x:  view.frame.origin.x,
            y:  view.frame.origin.y + translation.y
        )
        panGesture.setTranslation(CGPoint.zero, in: self.view)
    } else if panGesture.state == .ended {
        let velocity = panGesture.velocity(in: view)
        if velocity.y >= 150 {
            UIView.animate(withDuration: 0.2
                , animations: {
                    self.view.frame.origin = CGPoint(
                        x: self.view.frame.origin.x,
                        y: self.view.frame.size.height
                    )
            }, completion: { (isCompleted) in
                if isCompleted {
                    self.dismiss(animated: false, completion: nil)
                }
            })
        } else {
            UIView.animate(withDuration: 0.2, animations: {
                self.view.center = self.originalPosition!
            })
        }
    }

Answer 3

Aquí hay una extensión que hice basada en la respuesta de @Wilson:

// MARK: IMPORT STATEMENTS
import UIKit

// MARK: EXTENSION
extension UIViewController {

    // MARK: IS SWIPABLE - FUNCTION
    func isSwipable() {
        let panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(handlePanGesture(_:)))
        self.view.addGestureRecognizer(panGestureRecognizer)
    }

    // MARK: HANDLE PAN GESTURE - FUNCTION
    @objc func handlePanGesture(_ panGesture: UIPanGestureRecognizer) {
        let translation = panGesture.translation(in: view)
        let minX = view.frame.width * 0.135
        var originalPosition = CGPoint.zero

        if panGesture.state == .began {
            originalPosition = view.center
        } else if panGesture.state == .changed {
            view.frame.origin = CGPoint(x: translation.x, y: 0.0)

            if panGesture.location(in: view).x > minX {
                view.frame.origin = originalPosition
            }

            if view.frame.origin.x <= 0.0 {
                view.frame.origin.x = 0.0
            }
        } else if panGesture.state == .ended {
            if view.frame.origin.x >= view.frame.width * 0.5 {
                UIView.animate(withDuration: 0.2
                     , animations: {
                        self.view.frame.origin = CGPoint(
                            x: self.view.frame.size.width,
                            y: self.view.frame.origin.y
                        )
                }, completion: { (isCompleted) in
                    if isCompleted {
                        self.dismiss(animated: false, completion: nil)
                    }
                })
            } else {
                UIView.animate(withDuration: 0.2, animations: {
                    self.view.frame.origin = originalPosition
                })
            }
        }
    }

}

USO

Dentro de su controlador de vista desea ser deslizable:

override func viewDidLoad() {
    super.viewDidLoad()

    self.isSwipable()
}

y será descartado deslizando el dedo desde el extremo izquierdo del controlador de vista, como un controlador de navegación.

Answer 4

Aquí hay una solución de un archivo basada en la respuesta de @ wilson (gracias 👍) con las siguientes mejoras:

Lista de mejoras de la solución anterior

• Limite la panorámica para que la vista solo baje:
  • Evite la traducción horizontal actualizando solo la coordenada y de view.frame.origin
  • Evite desplazarse fuera de la pantalla al deslizar hacia arriba con let y = max(0, translation.y)
• También descarte el controlador de vista en función de dónde se suelta el dedo (predeterminado en la mitad inferior de la pantalla) y no solo en función de la velocidad del deslizamiento
• Muestre el controlador de vista como modal para asegurarse de que el controlador de vista anterior aparezca detrás y evite un fondo negro (debe responder su pregunta @ nguyễn-anh-việt)
• Eliminar currentPositionTouched y originalPosition innecesarios
• Exponga los siguientes parámetros:
  • minimumVelocityToHide : qué velocidad es suficiente para ocultar (el valor predeterminado es 1500)
  • minimumScreenRatioToHide : qué tan bajo es suficiente para ocultar (el valor predeterminado es 0.5)
  • animationDuration : qué tan rápido ocultamos / mostramos (el valor predeterminado es 0.2s)

Solución

Swift 3 y Swift 4:

//
//  PannableViewController.swift
//

import UIKit

class PannableViewController: UIViewController {
    public var minimumVelocityToHide: CGFloat = 1500
    public var minimumScreenRatioToHide: CGFloat = 0.5
    public var animationDuration: TimeInterval = 0.2

    override func viewDidLoad() {
        super.viewDidLoad()

        // Listen for pan gesture
        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(onPan(_:)))
        self.view.addGestureRecognizer(panGesture)
    }

    @objc func onPan(_ panGesture: UIPanGestureRecognizer) {

        func slideViewVerticallyTo(_ y: CGFloat) {
            self.view.frame.origin = CGPoint(x: 0, y: y)
        }

        switch panGesture.state {

        case .began, .changed:
            // If pan started or is ongoing then
            // slide the view to follow the finger
            let translation = panGesture.translation(in: view)
            let y = max(0, translation.y)
            self.slideViewVerticallyTo(y)

        case .ended:
            // If pan ended, decide it we should close or reset the view
            // based on the final position and the speed of the gesture
            let translation = panGesture.translation(in: view)
            let velocity = panGesture.velocity(in: view)
            let closing = (translation.y > self.view.frame.size.height * minimumScreenRatioToHide) ||
                          (velocity.y > minimumVelocityToHide)

            if closing {
                UIView.animate(withDuration: animationDuration, animations: {
                    // If closing, animate to the bottom of the view
                    self.slideViewVerticallyTo(self.view.frame.size.height)
                }, completion: { (isCompleted) in
                    if isCompleted {
                        // Dismiss the view when it dissapeared
                        self.dismiss(animated: false, completion: nil)
                    }
                })
            } else {
                // If not closing, reset the view to the top
                UIView.animate(withDuration: animationDuration, animations: {
                    self.slideViewVerticallyTo(0)
                })
            }

        default:
            // If gesture state is undefined, reset the view to the top
            UIView.animate(withDuration: animationDuration, animations: {
                self.slideViewVerticallyTo(0)
            })

        }
    }

    override init(nibName nibNameOrNil: String?, bundle nibBundleOrNil: Bundle?)   {
        super.init(nibName: nil, bundle: nil)
        self.modalPresentationStyle = .overFullScreen;
        self.modalTransitionStyle = .coverVertical;
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.modalPresentationStyle = .overFullScreen;
        self.modalTransitionStyle = .coverVertical;
    }
}

Answer 5

Compartiré cómo lo hice en Swift 3:

Resultado

Implementación

class MainViewController: UIViewController {

  @IBAction func click() {
    performSegue(withIdentifier: "showModalOne", sender: nil)
  }

}

class ModalOneViewController: ViewControllerPannable {
  override func viewDidLoad() {
    super.viewDidLoad()

    view.backgroundColor = .yellow
  }

  @IBAction func click() {
    performSegue(withIdentifier: "showModalTwo", sender: nil)
  }
}

class ModalTwoViewController: ViewControllerPannable {
  override func viewDidLoad() {
    super.viewDidLoad()

    view.backgroundColor = .green
  }
}

Donde los controladores de vista Modals heredan de una class que he construido ( ViewControllerPannable ) para hacerlos arrastrables y descartables cuando alcanzan cierta velocidad.

Clase ViewControllerPannable

class ViewControllerPannable: UIViewController {
  var panGestureRecognizer: UIPanGestureRecognizer?
  var originalPosition: CGPoint?
  var currentPositionTouched: CGPoint?

  override func viewDidLoad() {
    super.viewDidLoad()

    panGestureRecognizer = UIPanGestureRecognizer(target: self, action: #selector(panGestureAction(_:)))
    view.addGestureRecognizer(panGestureRecognizer!)
  }

  func panGestureAction(_ panGesture: UIPanGestureRecognizer) {
    let translation = panGesture.translation(in: view)

    if panGesture.state == .began {
      originalPosition = view.center
      currentPositionTouched = panGesture.location(in: view)
    } else if panGesture.state == .changed {
        view.frame.origin = CGPoint(
          x: translation.x,
          y: translation.y
        )
    } else if panGesture.state == .ended {
      let velocity = panGesture.velocity(in: view)

      if velocity.y >= 1500 {
        UIView.animate(withDuration: 0.2
          , animations: {
            self.view.frame.origin = CGPoint(
              x: self.view.frame.origin.x,
              y: self.view.frame.size.height
            )
          }, completion: { (isCompleted) in
            if isCompleted {
              self.dismiss(animated: false, completion: nil)
            }
        })
      } else {
        UIView.animate(withDuration: 0.2, animations: {
          self.view.center = self.originalPosition!
        })
      }
    }
  }
}

Answer 6

Descubrí una forma muy simple de hacer esto. Simplemente ponga el siguiente código en su controlador de vista:

Swift 4

//  Created by David Seek on 11/21/16.
//  Copyright © 2016 David Seek. All rights reserved.

import UIKit

class DismissAnimator : NSObject {
}

extension DismissAnimator : UIViewControllerAnimatedTransitioning {
    func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
        return 0.6
    }

    func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {

        let screenBounds = UIScreen.main.bounds
        let fromVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)
        let toVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)
        var x:CGFloat      = toVC!.view.bounds.origin.x - screenBounds.width
        let y:CGFloat      = toVC!.view.bounds.origin.y
        let width:CGFloat  = toVC!.view.bounds.width
        let height:CGFloat = toVC!.view.bounds.height
        var frame:CGRect   = CGRect(x: x, y: y, width: width, height: height)

        toVC?.view.alpha = 0.2

        toVC?.view.frame = frame
        let containerView = transitionContext.containerView

        containerView.insertSubview(toVC!.view, belowSubview: fromVC!.view)


        let bottomLeftCorner = CGPoint(x: screenBounds.width, y: 0)
        let finalFrame = CGRect(origin: bottomLeftCorner, size: screenBounds.size)

        UIView.animate(
            withDuration: transitionDuration(using: transitionContext),
            animations: {
                fromVC!.view.frame = finalFrame
                toVC?.view.alpha = 1

                x = toVC!.view.bounds.origin.x
                frame = CGRect(x: x, y: y, width: width, height: height)

                toVC?.view.frame = frame
            },
            completion: { _ in
                transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
            }
        )
    }
}

class Interactor: UIPercentDrivenInteractiveTransition {
    var hasStarted = false
    var shouldFinish = false
}

let transition: CATransition = CATransition()

func presentVCRightToLeft(_ fromVC: UIViewController, _ toVC: UIViewController) {
    transition.duration = 0.5
    transition.type = kCATransitionPush
    transition.subtype = kCATransitionFromRight
    fromVC.view.window!.layer.add(transition, forKey: kCATransition)
    fromVC.present(toVC, animated: false, completion: nil)
}

func dismissVCLeftToRight(_ vc: UIViewController) {
    transition.duration = 0.5
    transition.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
    transition.type = kCATransitionPush
    transition.subtype = kCATransitionFromLeft
    vc.view.window!.layer.add(transition, forKey: nil)
    vc.dismiss(animated: false, completion: nil)
}

func instantiatePanGestureRecognizer(_ vc: UIViewController, _ selector: Selector) {
    var edgeRecognizer: UIScreenEdgePanGestureRecognizer!
    edgeRecognizer = UIScreenEdgePanGestureRecognizer(target: vc, action: selector)
    edgeRecognizer.edges = .left
    vc.view.addGestureRecognizer(edgeRecognizer)
}

func dismissVCOnPanGesture(_ vc: UIViewController, _ sender: UIScreenEdgePanGestureRecognizer, _ interactor: Interactor) {
    let percentThreshold:CGFloat = 0.3
    let translation = sender.translation(in: vc.view)
    let fingerMovement = translation.x / vc.view.bounds.width
    let rightMovement = fmaxf(Float(fingerMovement), 0.0)
    let rightMovementPercent = fminf(rightMovement, 1.0)
    let progress = CGFloat(rightMovementPercent)

    switch sender.state {
    case .began:
        interactor.hasStarted = true
        vc.dismiss(animated: true, completion: nil)
    case .changed:
        interactor.shouldFinish = progress > percentThreshold
        interactor.update(progress)
    case .cancelled:
        interactor.hasStarted = false
        interactor.cancel()
    case .ended:
        interactor.hasStarted = false
        interactor.shouldFinish
            ? interactor.finish()
            : interactor.cancel()
    default:
        break
    }
}

Answer 7

En el objetivo C: aquí está el código

a la viewDidLoad

UISwipeGestureRecognizer *swipeRecognizer = [[UISwipeGestureRecognizer alloc]
                                             initWithTarget:self action:@selector(swipeDown:)];
swipeRecognizer.direction = UISwipeGestureRecognizerDirectionDown;
[self.view addGestureRecognizer:swipeRecognizer];

//Swipe Down Method

- (void)swipeDown:(UIGestureRecognizer *)sender{
[self dismissViewControllerAnimated:YES completion:nil];
}

Answer 8

Esta es mi clase simple para Drag ViewController desde el eje . Acabo de heredar tu clase de DraggableViewController.

MyCustomClass: DraggableViewController

Trabajar solo para ViewController presentado.

// MARK: - DraggableViewController

public class DraggableViewController: UIViewController {

    public let percentThresholdDismiss: CGFloat = 0.3
    public var velocityDismiss: CGFloat = 300
    public var axis: NSLayoutConstraint.Axis = .horizontal
    public var backgroundDismissColor: UIColor = .black {
        didSet {
            navigationController?.view.backgroundColor = backgroundDismissColor
        }
    }

    // MARK: LifeCycle

    override func viewDidLoad() {
        super.viewDidLoad()
        view.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: #selector(onDrag(_:))))
    }

    // MARK: Private methods

    @objc fileprivate func onDrag(_ sender: UIPanGestureRecognizer) {

        let translation = sender.translation(in: view)

        // Movement indication index
        let movementOnAxis: CGFloat

        // Move view to new position
        switch axis {
        case .vertical:
            let newY = min(max(view.frame.minY + translation.y, 0), view.frame.maxY)
            movementOnAxis = newY / view.bounds.height
            view.frame.origin.y = newY

        case .horizontal:
            let newX = min(max(view.frame.minX + translation.x, 0), view.frame.maxX)
            movementOnAxis = newX / view.bounds.width
            view.frame.origin.x = newX
        }

        let positiveMovementOnAxis = fmaxf(Float(movementOnAxis), 0.0)
        let positiveMovementOnAxisPercent = fminf(positiveMovementOnAxis, 1.0)
        let progress = CGFloat(positiveMovementOnAxisPercent)
        navigationController?.view.backgroundColor = UIColor.black.withAlphaComponent(1 - progress)

        switch sender.state {
        case .ended where sender.velocity(in: view).y >= velocityDismiss || progress > percentThresholdDismiss:
            // After animate, user made the conditions to leave
            UIView.animate(withDuration: 0.2, animations: {
                switch self.axis {
                case .vertical:
                    self.view.frame.origin.y = self.view.bounds.height

                case .horizontal:
                    self.view.frame.origin.x = self.view.bounds.width
                }
                self.navigationController?.view.backgroundColor = UIColor.black.withAlphaComponent(0)

            }, completion: { finish in
                self.dismiss(animated: true) //Perform dismiss
            })
        case .ended:
            // Revert animation
            UIView.animate(withDuration: 0.2, animations: {
                switch self.axis {
                case .vertical:
                    self.view.frame.origin.y = 0

                case .horizontal:
                    self.view.frame.origin.x = 0
                }
            })
        default:
            break
        }
        sender.setTranslation(.zero, in: view)
    }
}

Answer 9

He creado una extensión fácil de usar.

Simplemente inherente a su UIViewController con InteractiveViewController y ya está listo InteractiveViewController

llame al método showInteractive () desde su controlador para mostrar como interactivo.

Answer 10

Lo que está describiendo es una animación interactiva de transición personalizada . Está personalizando tanto la animación como el gesto de conducción de una transición, es decir, el descarte (o no) de un controlador de vista presentado. La forma más fácil de implementarlo es combinando un UIPanGestureRecognizer con un UIPercentDrivenInteractiveTransition.

Mi libro explica cómo hacer esto, y he publicado ejemplos (del libro). Este ejemplo particular es una situación diferente: la transición es lateral, no hacia abajo, y es para un controlador de barra de pestañas, no un controlador presentado, pero la idea básica es exactamente la misma:

https://github.com/mattneub/Programming-iOS-Book-Examples/blob/master/bk2ch06p296customAnimation2/ch19p620customAnimation1/AppDelegate.swift

Si descarga ese proyecto y lo ejecuta, verá que lo que está sucediendo es exactamente lo que está describiendo, excepto que es lateral: si el arrastre es más de la mitad, hacemos la transición, pero si no, cancelamos y volvemos a sitio.

Answer 11

Puede usar un UIPanGestureRecognizer para detectar el arrastre del usuario y mover la vista modal con él. Si la posición final está lo suficientemente abajo, la vista se puede descartar o animar de nuevo a su posición original.

Consulte esta respuesta para obtener más información sobre cómo implementar algo como esto.

Answer 12

Solo descarte vertical

override func viewDidLoad() {
    super.viewDidLoad()
    let gestureRecognizer = UIPanGestureRecognizer(target: self,
                                                   action: #selector(panGestureRecognizerHandler(_:)))
    view.addGestureRecognizer(gestureRecognizer)
}

@IBAction func panGestureRecognizerHandler(_ sender: UIPanGestureRecognizer) {
    let touchPoint = sender.location(in: view?.window)
    var initialTouchPoint = CGPoint.zero

    switch sender.state {
    case .began:
        initialTouchPoint = touchPoint
    case .changed:
        if touchPoint.y > initialTouchPoint.y {
            view.frame.origin.y = touchPoint.y - initialTouchPoint.y
        }
    case .ended, .cancelled:
        if touchPoint.y - initialTouchPoint.y > 200 {
            dismiss(animated: true, completion: nil)
        } else {
            UIView.animate(withDuration: 0.2, animations: {
                self.view.frame = CGRect(x: 0,
                                         y: 0,
                                         width: self.view.frame.size.width,
                                         height: self.view.frame.size.height)
            })
        }
    case .failed, .possible:
        break
    }
}

Answer 13

Swift 4.x, uso de pangesture

Manera simple

Vertical

class ViewConrtoller: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        view.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: #selector(onDrage(_:))))
    }

    @objc func onDrage(_ sender:UIPanGestureRecognizer) {
        let percentThreshold:CGFloat = 0.3
        let translation = sender.translation(in: view)

        let newX = ensureRange(value: view.frame.minX + translation.x, minimum: 0, maximum: view.frame.maxX)
        let progress = progressAlongAxis(newX, view.bounds.width)

        view.frame.origin.x = newX //Move view to new position

        if sender.state == .ended {
            let velocity = sender.velocity(in: view)
           if velocity.x >= 300 || progress > percentThreshold {
               self.dismiss(animated: true) //Perform dismiss
           } else {
               UIView.animate(withDuration: 0.2, animations: {
                   self.view.frame.origin.x = 0 // Revert animation
               })
          }
       }

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

Función auxiliar

func progressAlongAxis(_ pointOnAxis: CGFloat, _ axisLength: CGFloat) -> CGFloat {
        let movementOnAxis = pointOnAxis / axisLength
        let positiveMovementOnAxis = fmaxf(Float(movementOnAxis), 0.0)
        let positiveMovementOnAxisPercent = fminf(positiveMovementOnAxis, 1.0)
        return CGFloat(positiveMovementOnAxisPercent)
    }

    func ensureRange<T>(value: T, minimum: T, maximum: T) -> T where T : Comparable {
        return min(max(value, minimum), maximum)
    }

Manera difícil

Consulte esto -> https://github.com/satishVekariya/DraggableViewController

Answer 14

creó una demostración para arrastrar interactivamente hacia abajo para descartar el controlador de vista como el modo de descubrimiento de Snapchat. Consulte este github para un proyecto de muestra.