ZoomDismissalInteractionController

class ZoomDismissalInteractionController : NSObject

A custom interactive dismissal zoom transition for the transition from an ImagePagingCollectionViewController to an ImageCollectionViewController when the cell recognizes a pan gesture. It was built to mimic the transition used in the native iPhone Photos app.

This custom animation was documented and explained in complete detail in the links provided below.

See also

GitHub EditPlantLevelManager_notes.md.

  • The context provided to a transtion that has information about the source.

    Declaration

    Swift

    var transitionContext: UIViewControllerContextTransitioning?

  • The animator for the transition.

    Declaration

    Swift

    var animator: UIViewControllerAnimatedTransitioning?

  • The frame of the destination image view.

    Declaration

    Swift

    var fromReferenceImageViewFrame: CGRect?

  • The frame of the source image view.

    Declaration

    Swift

    var toReferenceImageViewFrame: CGRect?

  • The dismissal transition triggered by a panning gesture.

    The dismissal only completes if the gesture is released with the image below the starting location and the gesture not moving up the screen. It otherwise cancels and the transition view returns to the source image view.

    Declaration

    Swift

    func didPanWith(gestureRecognizer: UIPanGestureRecognizer)

    Parameters

    gestureRecognizer

    The pan gesture responsible for the dismissal.

  • Calculates the alpha of the backgroud of the source or destination view based on the displacement of the transition view.

    Declaration

    Swift

    func calculateBrackgroundAlphaFor(_ view: UIView, atDelta delta: CGFloat) -> CGFloat

    Parameters

    view

    The view being adjusted. It’s frame is used to measure the displacement.
    delta

    The current displacement of the image from its origin.

  • Calculate the scale of the transition image based on its displacement from its origin.

    Declaration

    Swift

    func calculateScaleIn(_ view: UIView, atDelta delta: CGFloat) -> CGFloat

    Parameters

    view

    The view being adjusted. It’s frame is used to measure the displacement.
    delta

    The current displacement of the image from its origin.

  • Called when an interactive transition is initiated. It is used here to prepare the transition controller.

    Declaration

    Swift

    func startInteractiveTransition(_ transitionContext: UIViewControllerContextTransitioning)