ZoomTransitionAnimator is a transition animator between view controllers. It zooms the whole scene together, not just the cell or image view you selected. Multi-layer zooming (zoom-in from view controller A to B and then to C) is supported. Although not an interactive transition animator, you can use it with UIPanGestureRecognizer
. As long as you return the correct frame of the target view in absolute space (UIScreen.main.coordinateSpace
), the animator will find it and zoom out from there.
To run the example project, clone the repo, and run pod install
from the Example directory first.
ZoomTransitionAnimator is available through CocoaPods. To install it, simply add the following line to your Podfile:
pod 'ZoomTransitionAnimator'
-
Initialize and return a
ZoomTransitionAnimator
object in yourUINavigationControllerDelegate
object.extension NavigationViewController: UINavigationControllerDelegate { func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationControllerOperation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? { switch (fromVC, toVC) { case (let zoomSourceVC as ZoomTransitionSource, let zoomDestinationVC as ZoomTransitionDestination): guard let operation = ZoomTransitionOperation(rawValue: operation.rawValue) else { return nil } return ZoomTransitionAnimator(duration: 0.45, damping: 0.75, source: zoomSourceVC, destination: zoomDestinationVC, operation: operation) default: return nil } } }
-
Apply both
ZoomTransitionSource
andZoomTransitionDestination
protocols to yourParentViewController
. Or if you only want the zoom animation to appear in only one direction, choose one of them to apply.extension ParentViewController: ZoomTransitionSource { func zoomTransitionAnimator(_ animator: ZoomTransitionAnimator, targetViewBeginningFrameFor operation: ZoomTransitionOperation) -> CGRect { switch operation { case .zoomIn: return selectedCellImageViewFrame case .zoomOut: fatalError() } } } extension ParentViewController: ZoomTransitionDestination { func zoomTransitionAnimator(_ animator: ZoomTransitionAnimator, targetViewFinalFrameFor operation: ZoomTransitionOperation) -> CGRect switch operation { case .zoomIn: fatalError() case .zoomOut: return selectedCellImageViewFrame } } }
Since the ParentViewController
is not going to be a zoom-in destination, you could put fatalError()
there. These cases were designed for when a ViewController
is both zoom-out destination and zoom-in destination. That is, multi-layer zooming.
-
Apply those protocols to your
ChildViewController
too.extension ChildViewController: ZoomTransitionSource { func zoomTransitionAnimator(_ animator: ZoomTransitionAnimator, targetViewBeginningFrameFor operation: ZoomTransitionOperation) -> CGRect { switch operation { case .zoomIn: fatalError() case .zoomOut: return imageViewFrame } } } extension ChildViewController: ZoomTransitionDestination { func zoomTransitionAnimator(_ animator: ZoomTransitionAnimator, targetViewFinalFrameFor operation: ZoomTransitionOperation) -> CGRect switch operation { case .zoomIn: return imageViewFrame case .zoomOut: fatalError() } } }
And that's it, really. You don't have to return any UIView
, just the frame of it. So if you want to zoom out from the content of a UIScrollView
, just calculate the frame with scrollView.contentOffset
and scrollView.contentSize
. No need to make a snapshot view anymore.
yesleon, yesleon@me.com
ZoomTransitionAnimator is available under the MIT license. See the LICENSE file for more info.