void FinishPan(UIPanGestureRecognizer panGestureRecognizer, nfloat verticalDelta, UIView viewToPan, CGPoint anchorPoint)
{
var fromView = _transitionContext?.GetViewFor(UITransitionContext.FromViewKey);
var velocityY = panGestureRecognizer.VelocityInView(panGestureRecognizer.View).Y;
var animationDuration = Math.Abs(velocityY) * PhotoDismissalInteractionControllerReturnToCenterVelocityAnimationRatio + 0.2;
var animationCurve = UIViewAnimationOptions.CurveEaseOut;
var finalPageViewCenterPount = anchorPoint;
var finalBackgroundAlpha = 1.0f;
var dismissDistance = (fromView == null) ? 0.0f : PhotoDismissalInteractionControllerPanDismissDistanceRatio * fromView.Bounds.Height;
var isDismissing = Math.Abs(verticalDelta) > dismissDistance;
var didAnimateUsingAnimator = false;
if (isDismissing)
{
if (ShouldAnimateUsingAnimator)
{
Animator.AnimateTransition(_transitionContext);
didAnimateUsingAnimator = true;
}
else
{
var isPositiveDelta = verticalDelta >= 0;
var modifier = isPositiveDelta ? 1 : -1;
if (fromView == null)
{
finalPageViewCenterPount = new CGPoint(0.0f, 0.0f);
}
else
{
var finalCenterY = fromView.Bounds.GetMidY() + modifier * fromView.Bounds.Height;
finalPageViewCenterPount = new CGPoint(fromView.Center.X, finalCenterY);
}
animationDuration = Math.Abs(finalPageViewCenterPount.Y - viewToPan.Center.Y) / Math.Abs(velocityY);
animationDuration = Math.Min(animationDuration, PhotoDismissalInteractionControllerPanDismissMaximumDuration);
animationCurve = UIViewAnimationOptions.CurveEaseOut;
finalBackgroundAlpha = 0.0f;
}
}
if (!didAnimateUsingAnimator)
{
UIView.Animate(animationDuration, 0,
animationCurve,
() => {
viewToPan.Center = finalPageViewCenterPount;
fromView.BackgroundColor = fromView.BackgroundColor.ColorWithAlpha(finalBackgroundAlpha);
},
() =>
{
if (isDismissing)
{
_transitionContext.FinishInteractiveTransition();
}
else
{
_transitionContext.CancelInteractiveTransition();
}
if (ViewToHideWhenBeginningTransition != null)
{
ViewToHideWhenBeginningTransition.Alpha = 1.0f;
}
_transitionContext.CompleteTransition(isDismissing && !_transitionContext.TransitionWasCancelled);
_transitionContext = null;
}
);
}
else
{
_transitionContext = null;
}
}