是否有可以在 iOS 10 中看到的卡片视图 UI 的公共 API？

Question

The Music app in iOS 10 adopts a new card-like appearance: Now Playing screen slides up, while the view below in the hierarchy zooms out, protruding slightly at the top of the screen.

Here is the example from Mail compose window:

This metaphor can also be seen in Overcast, the popular podcast player:

Is there a function in UIKit for achieving this card-like appearance?

Answer 1

You can build the segue in interface builder. Selecting modal segue from ViewController to CardViewController .

For your CardViewController :

import UIKit

class CardViewController: UIViewController {

  required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    self.commonInit()
  }

  override init(nibName nibNameOrNil: String!, bundle nibBundleOrNil: Bundle!)  {
    super.init(nibName: nibNameOrNil, bundle: nibBundleOrNil)

    self.commonInit()
  }

  func commonInit() {
    self.modalPresentationStyle = .custom
    self.transitioningDelegate = self
  }

  override func viewDidLoad() {
    super.viewDidLoad()

    roundViews()
  }

  func roundViews() {
    view.layer.cornerRadius = 8
    view.clipsToBounds = true
  }

}

then add this extension:

extension CardViewController: UIViewControllerTransitioningDelegate {

  func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? {
    if presented == self {
      return CardPresentationController(presentedViewController: presented, presenting: presenting)
    }
    return nil
  }

  func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    if presented == self {
      return CardAnimationController(isPresenting: true)
    } else {
      return nil
    }
  }

  func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
    if dismissed == self {
      return CardAnimationController(isPresenting: false)
    } else {
      return nil
    }
  }

}

Finally, you will need 2 more classes:

import UIKit

class CardPresentationController: UIPresentationController {

  lazy var dimmingView :UIView = {
    let view = UIView(frame: self.containerView!.bounds)
    view.backgroundColor = UIColor(red: 0.0, green: 0.0, blue: 0.0, alpha: 0.3)
    view.layer.cornerRadius = 8
    view.clipsToBounds = true
    return view
  }()

  override func presentationTransitionWillBegin() {

    guard
      let containerView = containerView,
      let presentedView = presentedView
      else {
        return
    }

    // Add the dimming view and the presented view to the heirarchy
    dimmingView.frame = containerView.bounds
    containerView.addSubview(dimmingView)
    containerView.addSubview(presentedView)

    // Fade in the dimming view alongside the transition
    if let transitionCoordinator = self.presentingViewController.transitionCoordinator {
      transitionCoordinator.animate(alongsideTransition: {(context: UIViewControllerTransitionCoordinatorContext!) -> Void in
        self.dimmingView.alpha = 1.0
      }, completion:nil)
    }
  }

  override func presentationTransitionDidEnd(_ completed: Bool)  {
    // If the presentation didn't complete, remove the dimming view
    if !completed {
      self.dimmingView.removeFromSuperview()
    }
  }

  override func dismissalTransitionWillBegin()  {
    // Fade out the dimming view alongside the transition
    if let transitionCoordinator = self.presentingViewController.transitionCoordinator {
      transitionCoordinator.animate(alongsideTransition: {(context: UIViewControllerTransitionCoordinatorContext!) -> Void in
        self.dimmingView.alpha  = 0.0
      }, completion:nil)
    }
  }

  override func dismissalTransitionDidEnd(_ completed: Bool) {
    // If the dismissal completed, remove the dimming view
    if completed {
      self.dimmingView.removeFromSuperview()
    }
  }

  override var frameOfPresentedViewInContainerView : CGRect {

    // We don't want the presented view to fill the whole container view, so inset it's frame
    let frame = self.containerView!.bounds;
    var presentedViewFrame = CGRect.zero
    presentedViewFrame.size = CGSize(width: frame.size.width, height: frame.size.height - 40)
    presentedViewFrame.origin = CGPoint(x: 0, y: 40)

    return presentedViewFrame
  }

  override func viewWillTransition(to size: CGSize, with transitionCoordinator: UIViewControllerTransitionCoordinator) {
    super.viewWillTransition(to: size, with: transitionCoordinator)

    guard
      let containerView = containerView
      else {
        return
    }

    transitionCoordinator.animate(alongsideTransition: {(context: UIViewControllerTransitionCoordinatorContext!) -> Void in
      self.dimmingView.frame = containerView.bounds
    }, completion:nil)
  }

}

and:

import UIKit


class CardAnimationController: NSObject {

  let isPresenting :Bool
  let duration :TimeInterval = 0.5

  init(isPresenting: Bool) {
    self.isPresenting = isPresenting

    super.init()
  }
}

// MARK: - UIViewControllerAnimatedTransitioning

extension CardAnimationController: UIViewControllerAnimatedTransitioning {

  func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
    return self.duration
  }

  func animateTransition(using transitionContext: UIViewControllerContextTransitioning)  {
    let fromVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.from)
    let fromView = fromVC?.view
    let toVC = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to)
    let toView = toVC?.view

    let containerView = transitionContext.containerView

    if isPresenting {
      containerView.addSubview(toView!)
    }

    let bottomVC = isPresenting ? fromVC : toVC
    let bottomPresentingView = bottomVC?.view

    let topVC = isPresenting ? toVC : fromVC
    let topPresentedView = topVC?.view
    var topPresentedFrame = transitionContext.finalFrame(for: topVC!)
    let topDismissedFrame = topPresentedFrame
    topPresentedFrame.origin.y -= topDismissedFrame.size.height
    let topInitialFrame = topDismissedFrame
    let topFinalFrame = isPresenting ? topPresentedFrame : topDismissedFrame
    topPresentedView?.frame = topInitialFrame

    UIView.animate(withDuration: self.transitionDuration(using: transitionContext),
                   delay: 0,
                   usingSpringWithDamping: 300.0,
                   initialSpringVelocity: 5.0,
                   options: [.allowUserInteraction, .beginFromCurrentState], //[.Alert, .Badge]
      animations: {
        topPresentedView?.frame = topFinalFrame
        let scalingFactor : CGFloat = self.isPresenting ? 0.92 : 1.0
        bottomPresentingView?.transform = CGAffineTransform.identity.scaledBy(x: scalingFactor, y: scalingFactor)

    }, completion: {
      (value: Bool) in
      if !self.isPresenting {
        fromView?.removeFromSuperview()
      }
    })


    if isPresenting {
      animatePresentationWithTransitionContext(transitionContext)
    } else {
      animateDismissalWithTransitionContext(transitionContext)
    }
  }

  func animatePresentationWithTransitionContext(_ transitionContext: UIViewControllerContextTransitioning) {

    let containerView = transitionContext.containerView
    guard
      let presentedController = transitionContext.viewController(forKey: UITransitionContextViewControllerKey.to),
      let presentedControllerView = transitionContext.view(forKey: UITransitionContextViewKey.to)
      else {
        return
    }

    // Position the presented view off the top of the container view
    presentedControllerView.frame = transitionContext.finalFrame(for: presentedController)
    presentedControllerView.center.y += containerView.bounds.size.height

    containerView.addSubview(presentedControllerView)

    // Animate the presented view to it's final position
    UIView.animate(withDuration: self.duration, delay: 0.0, usingSpringWithDamping: 1.0, initialSpringVelocity: 0.0, options: .allowUserInteraction, animations: {
      presentedControllerView.center.y -= containerView.bounds.size.height
    }, completion: {(completed: Bool) -> Void in
      transitionContext.completeTransition(completed)
    })
  }

  func animateDismissalWithTransitionContext(_ transitionContext: UIViewControllerContextTransitioning) {

    let containerView = transitionContext.containerView
    guard
      let presentedControllerView = transitionContext.view(forKey: UITransitionContextViewKey.from)
      else {
        return
    }

    // Animate the presented view off the bottom of the view
    UIView.animate(withDuration: self.duration, delay: 0.0, usingSpringWithDamping: 1.0, initialSpringVelocity: 0.0, options: .allowUserInteraction, animations: {
      presentedControllerView.center.y += containerView.bounds.size.height
    }, completion: {(completed: Bool) -> Void in
      transitionContext.completeTransition(completed)
    })
  }
}

Finally, in order to animate the CardViewController closing, hook your closing button to FirstResponder selecting dismiss and add this method to ViewController :

func dismiss(_ segue: UIStoryboardSegue) {
    self.dismiss(animated: true, completion: nil)
}

Answer 2

Apple show how to do this using UIViewPropertyAnimator in WWDC 2017 Session 230: Advanced Animations with UIKit

The basic idea is that you add a child view controller, and position it mostly off-screen. When tapped/panned you animate the child view controller's frame.

import UIKit

class CardViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .red
    }
}

class ViewController: UIViewController {
    private let cardViewController = CardViewController()
    private var cardHiddenConstraint: NSLayoutConstraint!
    private var cardVisibleConstraint: NSLayoutConstraint!

    override func viewDidLoad() {
        super.viewDidLoad()

        addChild(cardViewController)
        let cardViewControllerView = cardViewController.view!
        cardViewControllerView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(cardViewControllerView)

        cardHiddenConstraint = cardViewControllerView.topAnchor.constraint(equalTo: view.bottomAnchor, constant: -50)
        cardVisibleConstraint = cardViewControllerView.topAnchor.constraint(equalTo: view.topAnchor, constant: 50)

        let cardViewControllerViewConstraints = [
            cardViewControllerView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            cardViewControllerView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            cardHiddenConstraint!,
            cardViewControllerView.heightAnchor.constraint(equalTo: view.heightAnchor)
        ]
        NSLayoutConstraint.activate(cardViewControllerViewConstraints)

        cardViewController.didMove(toParent: self)

        let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(handleTapGesture(_:)))
        cardViewController.view.addGestureRecognizer(tapGestureRecognizer)
    }

    @objc private func handleTapGesture(_ gestureRecognizer: UITapGestureRecognizer) {
        let frameAnimator = UIViewPropertyAnimator(duration: 0.3, dampingRatio: 1) {
            if self.cardHiddenConstraint.isActive {
                self.cardHiddenConstraint.isActive = false
                self.cardVisibleConstraint.isActive = true
            } else {
                self.cardVisibleConstraint.isActive = false
                self.cardHiddenConstraint.isActive = true
            }
            self.view.layoutIfNeeded()
        }
        frameAnimator.startAnimation()
    }
}

Answer 3

Ok, I'll try to give you a compact solution with a minimum of code.

Fast solution. You need to present a controller modally with modalPresentationStyle - property set to .overCurrentContext . You can set the value before preset(controller:...) -method get called or in prepare(for:...) -one if it's a segue transition. For sliding up use modalTransitionStyle set to .coverVertical .

To "zoom out" source view just update its bounds in viewWill(Diss)appear -methods. In most of cases this will work.

Don't forget to set your modal controller background view transparent so the underlying view still be visible.

Sliding up/down smoothly. You need to setup a transition between the controllers in a proper way. If you look closer to Apple music app, you'll see a way to hide top controller with slide down gesture. You can customise your view (dis)appearance too. Take a look at this article . It uses UIKit -methods only. Unfortunately this way requires lots of code, but you can use 3rd party libraries to setup transitions. Like this one .

Answer 4

如果您愿意添加第三方依赖项，请尝试SPStorkController ，它是最新的（撰写本文时为 Swift 4.2）并且只需最少的配置即可使用。