how to create a zoom transition using custom navigation transition? - animation

Question

I'm new to navigation transition. I'm using Swift language for development.
What i'm trying to do is, whenever user click on the tableview cell the new view will open and it look like it coming from the image view of the cell.
I created a class of UIViewControllerAnimatedTransitioning.
class ThumbnailZoomTransitionAnimator: NSObject, UIViewControllerAnimatedTransitioning {
private let duration: TimeInterval = 0.5
var operation: UINavigationControllerOperation = .push
var thumbnailFrame = CGRect.zero
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return duration
}
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
let presenting = operation == .push
// Determine which is the master view and which is the detail view that we're navigating to and from. The container view will house the views for transition animation.
let containerView = transitionContext.containerView
guard let toView = transitionContext.view(forKey: UITransitionContextViewKey.to) else { return }
guard let fromView = transitionContext.view(forKey: UITransitionContextViewKey.from) else { return }
let storyFeedView = presenting ? fromView : toView
let storyDetailView = presenting ? toView : fromView
// Determine the starting frame of the detail view for the animation. When we're presenting, the detail view will grow out of the thumbnail frame. When we're dismissing, the detail view will shrink back into that same thumbnail frame.
var initialFrame = presenting ? thumbnailFrame : storyDetailView.frame
let finalFrame = presenting ? storyDetailView.frame : thumbnailFrame
// Resize the detail view to fit within the thumbnail's frame at the beginning of the push animation and at the end of the pop animation while maintaining it's inherent aspect ratio.
let initialFrameAspectRatio = initialFrame.width / initialFrame.height
let storyDetailAspectRatio = storyDetailView.frame.width / storyDetailView.frame.height
if initialFrameAspectRatio > storyDetailAspectRatio {
initialFrame.size = CGSize(width: initialFrame.height * storyDetailAspectRatio, height: initialFrame.height)
}
else {
initialFrame.size = CGSize(width: initialFrame.width, height: initialFrame.width / storyDetailAspectRatio)
}
let finalFrameAspectRatio = finalFrame.width / finalFrame.height
var resizedFinalFrame = finalFrame
if finalFrameAspectRatio > storyDetailAspectRatio {
resizedFinalFrame.size = CGSize(width: finalFrame.height * storyDetailAspectRatio, height: finalFrame.height)
}
else {
resizedFinalFrame.size = CGSize(width: finalFrame.width, height: finalFrame.width / storyDetailAspectRatio)
}
// Determine how much the detail view needs to grow or shrink.
let scaleFactor = resizedFinalFrame.width / initialFrame.width
let growScaleFactor = presenting ? scaleFactor: 1/scaleFactor
let shrinkScaleFactor = 1/growScaleFactor
if presenting {
// Shrink the detail view for the initial frame. The detail view will be scaled to CGAffineTransformIdentity below.
storyDetailView.transform = CGAffineTransform(scaleX: shrinkScaleFactor, y: shrinkScaleFactor)
storyDetailView.center = CGPoint(x: thumbnailFrame.midX, y: thumbnailFrame.midY)
storyDetailView.clipsToBounds = true
}
// Set the initial state of the alpha for the master and detail views so that we can fade them in and out during the animation.
storyDetailView.alpha = presenting ? 0 : 1
storyFeedView.alpha = presenting ? 1 : 0
// Add the view that we're transitioning to to the container view that houses the animation.
containerView.addSubview(toView)
containerView.bringSubview(toFront: storyDetailView)
// Animate the transition.
UIView.animate(withDuration: duration, delay: 0.0, usingSpringWithDamping: 1, initialSpringVelocity: 1.0, options: .curveEaseInOut, animations: {
// Fade the master and detail views in and out.
storyDetailView.alpha = presenting ? 1 : 0
storyFeedView.alpha = presenting ? 0 : 1
if presenting {
// Scale the master view in parallel with the detail view (which will grow to its inherent size). The translation gives the appearance that the anchor point for the zoom is the center of the thumbnail frame.
let scale = CGAffineTransform(scaleX: growScaleFactor, y: growScaleFactor)
let translate = CGAffineTransform(translationX: storyFeedView.frame.midX - self.thumbnailFrame.midX, y: storyFeedView.frame.midY - self.thumbnailFrame.midY)
storyFeedView.transform = translate.concatenating(scale)
storyDetailView.transform = .identity
}
else {
// Return the master view to its inherent size and position and shrink the detail view.
storyFeedView.transform = .identity
storyDetailView.transform = CGAffineTransform(scaleX: shrinkScaleFactor, y: shrinkScaleFactor)
}
// Move the detail view to the final frame position.
storyDetailView.center = CGPoint(x: finalFrame.midX, y: finalFrame.midY)
}) { finished in
transitionContext.completeTransition(finished)
}
}
}
When i click on the cell then new controller open. This functionality is working correctly. But whenever i'm going back then my previous controller get disappear.
Is i'm doing something wrong here ,
// Animate the transition.
UIView.animate(withDuration: duration, delay: 0.0, usingSpringWithDamping: 1, initialSpringVelocity: 1.0, options: .curveEaseInOut, animations: {
// Fade the master and detail views in and out.
storyDetailView.alpha = presenting ? 1 : 0
storyFeedView.alpha = presenting ? 0 : 1
if presenting {
// Scale the master view in parallel with the detail view (which will grow to its inherent size). The translation gives the appearance that the anchor point for the zoom is the center of the thumbnail frame.
let scale = CGAffineTransform(scaleX: growScaleFactor, y: growScaleFactor)
let translate = CGAffineTransform(translationX: storyFeedView.frame.midX - self.thumbnailFrame.midX, y: storyFeedView.frame.midY - self.thumbnailFrame.midY)
storyFeedView.transform = translate.concatenating(scale)
storyDetailView.transform = .identity
}
else {
// Return the master view to its inherent size and position and shrink the detail view.
storyFeedView.transform = .identity
storyDetailView.transform = CGAffineTransform(scaleX: shrinkScaleFactor, y: shrinkScaleFactor)
}
// Move the detail view to the final frame position.
storyDetailView.center = CGPoint(x: finalFrame.midX, y: finalFrame.midY)
}) { finished in
transitionContext.completeTransition(finished)
}
I'm trying to Scale the master view in parallel with the detail view (which will grow to its inherent size). The translation gives the appearance that the anchor point for the zoom is the center of the thumbnail frame.
It will give zoomIn ZoomOut effect when user go back to previous controller. But When i trying to do this then my previous controller disappear.
I wanted to do like zoom transition like apple do in their apps.