how to flip a view around the y axis? Is this a bug?

[patchthecode]

how to flip a view around the y axis?
With my code bwloe, the view does indeed flip for the first 4 times. Then it begins to flip in all sorts of weird angles and starts messing. If my code below correct?

Here is my code:

    sender.userInteractionEnabled = false

    let cell = self.table.cellForRowAtIndexPath(NSIndexPath(forRow: index, inSection: section)) as! BookingTableViewCell
    cell.buttonStateIsSelected = !cell.buttonStateIsSelected

    let layer = sender.layer

    // First let's remove any existing animations
    layer.pop_removeAllAnimations()
    layer.removeAllAnimations()
    let rotation: POPSpringAnimation = POPSpringAnimation(propertyNamed:kPOPLayerRotationY)

    rotation.fromValue = M_PI

    rotation.completionBlock = {(anim: POPAnimation! , finished: Bool) -> Void in
        if cell.buttonStateIsSelected == true {
            sender.setTitle("SideB", forState: UIControlState.Normal)
        } else {
            sender.setTitle("SideA", forState: UIControlState.Normal)
        }
        layer.pop_removeAllAnimations()
        sender.userInteractionEnabled = true
    }

    layer.pop_addAnimation(rotation, forKey: "rotation")

[grp]

It doesn't look like you're setting a toValue here — are you relying on that being a default? I wonder if that changes when you press it multiple times?

[patchthecode]

I have changed the code to have a to value of Zero (0). And I am getting the same problem. Do you have any code that i may see that has a simple flip rotation?

Here is my redone method in full. It is still failing after the 3rd click.

@IBAction func clicky(sender: UIButton) {
    sender.userInteractionEnabled = false
    let layer = sender.layer

    // First let's remove any existing animations
    layer.pop_removeAllAnimations()
    layer.removeAllAnimations()
    let rotation: POPSpringAnimation = POPSpringAnimation(propertyNamed:kPOPLayerRotationY)

    rotation.fromValue = M_PI
    rotation.toValue = 0

    rotation.completionBlock = {(anim: POPAnimation! , finished: Bool) -> Void in
        layer.pop_removeAllAnimations()
        sender.userInteractionEnabled = true
    }

    layer.pop_addAnimation(rotation, forKey: "rotation")
}

Can you try copying this code and running it to see the same bug i am seeing?

[grp]

I haven't tried this animation specifically before, no. My question is mostly about what you said about it working a few times — if it works once, it should work again if all the other properties on the layer are the same. Is that understanding right?

[patchthecode]

Ok i see. Yes, if i tab the button once, it flips correctly. 2nd time works as well as 3rd time. By about the 4th tap, the view begins messing up badly. I have put a question about it on stack overflow about it and someone gave me an answer yesterday. https://stackoverflow.com/questions/35251571/how-to-flip-a-uiview-horizontally-using-facebook-pop-ios-framework

It does seem to be a bug. I wonder why such a simple animation has not been fixed yet.