使用CATransition自解散时隐藏黑色渐变

Question

I want to make my viewController to dismiss to an old viewController with animation. But when I use CATransition my viewController and old viewController fades black. Is there any way I can make it not to fade?

let transition = CATransition()
transition.duration = 1.0
transition.type = kCATransitionPush
transition.subtype = kCATransitionFromLeft
view.window!.layer.add(transition, forKey: kCATransition)
self.dismiss(animated: false, completion: nil)

Answer 1

Read more about transition here and try to modify available parameters to achieve required effects.

Good undocumented info about transition available here .

In case you want some good solution - you should prepare custom transition for your screen - check this WWDC video

Alternative fast (but not the best) solution may be manual control of presentation/dismiss in your viewController:

import UIKit

final class AnimatableViewController: UIViewController {

    private var panStartLocation:CGPoint = CGPoint.zero
    private var panPrevLocation:CGPoint = CGPoint.zero

    var onClose:(()->())?

    // MARK: - LifeCycle

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

        openAnimation()
    }

    // MARK: - IBAction

    @objc private func closeButtonAction(_ sender: UIButton) {
        dismiss(animated: true, completion: { [weak self] in
            self?.onClose?()
        })
    }

    // MARK: - Gestures

    @IBAction private func didDetectPan(_ sender: UIPanGestureRecognizer) {
        switch sender.state {
            case .began:
                panStartLocation = sender.location(in: navigationController?.view)
                panPrevLocation = panStartLocation
            case .cancelled, .ended:
                finishAnimation()
            case .changed:
                let newPoint:CGPoint = sender.location(in: navigationController?.view)
                let dy:CGFloat = newPoint.y - panPrevLocation.y
                var newPosition:CGPoint = view.center

                if (newPoint.y - panStartLocation.y > 0) {
                    newPosition.y += dy
                } else {
                    newPosition.y = self.view.bounds.height / 2
                }
                view.center = newPosition
                panPrevLocation = newPoint
            default:
                break
        }
    }

    //MARK: Animation

    private func finishAnimation() {
        let center:CGPoint = view.center
        if (center.y > self.view.bounds.height / 2 * 1.35) {
            closeAnimation()
        } else {
            openAnimation()
        }
    }

    private func closeAnimation() {
        let fullAnimTime:CGFloat = 0.5
        let endPoint:CGPoint = CGPoint(x:view.center.x, y:view.bounds.height / 2 * 3)
        let animTime:CGFloat = ((endPoint.y - view.center.y) / self.view.bounds.height) * fullAnimTime

        UIView.animate(withDuration: TimeInterval(animTime), animations: { [weak self] in
            self?.view.center = endPoint
            }, completion: { [weak self] _ in
                self?.dismiss(animated: false, completion: {
                    self?.onClose?()
                })
        })
    }

    private func openAnimation() {
        let fullAnimTime:CGFloat = 0.5
        let endPoint:CGPoint = CGPoint(x: view.center.x, y:self.view.bounds.height / 2)
        let animTime:CGFloat = ((view.center.y - endPoint.y) / (self.view.bounds.height / 2)) * fullAnimTime
        UIView.animate(withDuration: TimeInterval(animTime)) { [weak self] in
            self?.view.center = endPoint
        }
    }
}

extension AnimatableViewController: UIGestureRecognizerDelegate {
    // MARK: - UIGestureRecognizerDelegate

    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        if gestureRecognizer is UIPanGestureRecognizer && otherGestureRecognizer is UIPanGestureRecognizer {
            return false
        }
        return true
    }
}

In storyboard don't forget to set you segue parameters as:

And add panGesture to your root view or any additional pan Gesture to top most view, that can be used for pan - in my case - i just add pan to rootView:

Result: