Have tried to replicate this with a simple example using a UISlider and UIViewPropertyAnimator and can't replicate, so I think it might be something to do with custom transitions, here is the code for that:
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
let containerView = transitionContext.containerView
guard let purchaseDetailVC = transitionContext.viewController(forKey: .to) as? PurchaseDetailViewController,
let purchaseDetailView = transitionContext.view(forKey: .to) else {
return
}
let toFrame = transitionContext.finalFrame(for: purchaseDetailVC)
let dismissButton = UIButton()
dismissButton.setBackgroundImage( imageLiteral(resourceName: "icon-close"), for: .normal)
dismissButton.translatesAutoresizingMaskIntoConstraints = false
let cardView: PurchaseView = PurchaseView(frame: .zero)
cardView.translatesAutoresizingMaskIntoConstraints = false
cardView.purchasable = fromCell.purchaseView.purchasable
cardView.buyButtonState = fromCell.purchaseView.buyButtonState
cardView.buyButton.titleLabel?.font = UIFont.preferredFont(forTextStyle: .title3).withWeight(.medium)
cardView.addSubview(dismissButton)
let buttonConstraints = [
dismissButton.topAnchor.constraint(equalTo: cardView.topAnchor, constant: 20),
dismissButton.trailingAnchor.constraint(equalTo: cardView.trailingAnchor, constant: -20)
]
NSLayoutConstraint.activate(buttonConstraints)
let detailBGView = UIView(frame: .zero)
detailBGView.translatesAutoresizingMaskIntoConstraints = false
detailBGView.backgroundColor = purchaseDetailVC.tableView.backgroundColor
// Card view constraints
containerView.addSubview(detailBGView)
let bgVerticalConstraint = detailBGView.centerYAnchor.constraint(equalTo: containerView.centerYAnchor, constant: (fromFrame.height/2 + fromFrame.minY) - containerView.bounds.height/2)
let bgConstraints = [
bgVerticalConstraint,
detailBGView.centerXAnchor.constraint(equalTo: containerView.centerXAnchor)
]
NSLayoutConstraint.activate(bgConstraints)
let bgWidthConstraint = detailBGView.widthAnchor.constraint(equalToConstant: fromFrame.width)
let bgHeightConstraint = detailBGView.heightAnchor.constraint(equalToConstant: fromFrame.height)
NSLayoutConstraint.activate([bgWidthConstraint, bgHeightConstraint])
containerView.addSubview(cardView)
let verticalConstraint = cardView.centerYAnchor.constraint(equalTo: containerView.centerYAnchor, constant: (fromFrame.height/2 + fromFrame.minY) - containerView.bounds.height/2)
let cardConstraints = [
verticalConstraint,
cardView.centerXAnchor.constraint(equalTo: containerView.centerXAnchor)
]
NSLayoutConstraint.activate(cardConstraints)
let cardWidthConstraint = cardView.widthAnchor.constraint(equalToConstant: fromFrame.width)
let cardHeightConstraint = cardView.heightAnchor.constraint(equalToConstant: fromFrame.height)
NSLayoutConstraint.activate([cardWidthConstraint, cardHeightConstraint])
cardView.cornerRadius = 12
cardView.cornerCurve = .continuous
detailBGView.cornerRadius = 12
detailBGView.cornerCurve = .continuous
fromCell.isHidden = true
fromCell.transform = .identity
containerView.layoutIfNeeded()
springAnimator.addAnimations {
bgVerticalConstraint.constant = toFrame.minY/2
verticalConstraint.constant = (purchaseDetailVC.headerHeight/2 - toFrame.height/2 + toFrame.minY/2)
cardView.topConstraint.constant = purchaseDetailVC.purchaseView.topConstraint.constant
containerView.layoutIfNeeded()
}
springAnimator.startAnimation()
let expandingAnimator = UIViewPropertyAnimator(duration: springAnimator.duration * 0.6, curve: .linear)
expandingAnimator.addAnimations {
cardView.containerView.borderWidth = 0.0
cardView.buyButton.style = .onDarkBackground
cardView.headlineHidden = true
cardWidthConstraint.constant = toFrame.width
cardHeightConstraint.constant = purchaseDetailVC.headerHeight
bgWidthConstraint.constant = toFrame.width
bgHeightConstraint.constant = toFrame.height
// Must use layer because using view var breaks this for some reason
cardView.layer.cornerRadius = 0.0
detailBGView.layer.cornerRadius = 0.0
containerView.layoutIfNeeded()
}
expandingAnimator.startAnimation()
springAnimator.addCompletion { (_) in
detailBGView.removeFromSuperview()
cardView.removeFromSuperview()
containerView.addSubview(purchaseDetailView)
let success = !transitionContext.transitionWasCancelled
transitionContext.completeTransition(success)
}
}
