UISnapBehaviour in x-axis only - ios

Question

Is there anyway to get UISnapBevahiour to only work along a linear x-axis?
I want the exact behaviour of a UISnapBehaviour but don't want it to 'shake' into position on both x & y axis, just the x axis.
This is for a UIView inside my contentView of a table cell.
// UIKitDynamics
self.animator = [[UIDynamicAnimator alloc] initWithReferenceView:self];
CGPoint centerPoint = self.contentView.center;
self.snapBehaviour = [[UISnapBehavior alloc] initWithItem:self.frontView snapToPoint:centerPoint];
[self.snapBehaviour setDamping:1.0f];
[self.animator addBehavior:self.snapBehaviour];
UIDynamicItemBehavior *itemBehaviour = [[UIDynamicItemBehavior alloc] initWithItems:#[self.frontView]];
itemBehaviour.elasticity = 0.0f;
itemBehaviour.allowsRotation = NO;
[self.animator addBehavior:itemBehaviour];

Answer 1

From UIDynamicBehavior documentation of it's action block:
#property(nonatomic, copy) void (^action)(void)
The dynamic animator calls the action block on every animation step.
So when creating your behaviour, do something like this:
UIView *view = ...
UIAttachmentBehavior *attachment = [[UIAttachmentBehavior alloc] initWithItem:view attachedToAnchor:point];
CGFloat xCoordinate = view.frame.origin.x;
attachment.action = ^{
if (view.frame.origin.x != xCoordinate) {
CGRect frame = view.frame;
frame.origin.x = xCoordinate;
view.frame = frame;
}
};
[self.dynamicAnimator addBehavior:attachment];
In my example I use a UIAttachmentBehavior but this method will also work for any other subclass of UIDynamicBehavior, in your case a UISnapBehavior.

Answer 2

I'll post the code I used to do a similar thing, as I mentioned in my comment it used UIView animation that leverage UIKit Dynamics underneath as opposed to using them directly...
[UIView animateWithDuration:0.5
delay:0.0
usingSpringWithDamping:0.5
initialSpringVelocity:0.3
options:UIViewAnimationOptionCurveEaseIn
animations:^{
[toView setFrame:_modalFrame];
}
completion:^(BOOL finished) {
[self.context completeTransition:YES];
}];
This presents modal view which springs up and oscillates a bit on presentation.