Animation and Focus issue

Hi,

I am having a bit of a problem wherein there is some unexpected, by me anyway, interaction between having a UIImageView's position animating and being able to focus on UIButtons. I have the following animation going on:

    func animateCloud1() {
        let duration : NSTimeInterval = 40.0
        let delay : NSTimeInterval = 0.0
        let options = UIViewAnimationOptions.CurveLinear
   
        let yPosition : CGFloat = CGFloat( arc4random_uniform(400))
   
        cloud1.frame = CGRectMake(-280, yPosition, 280, 320)
   
        UIView.animateWithDuration(duration, delay: delay, options: options, animations: {
            self.cloud1.frame = CGRectMake(2200, yPosition, 280, 320)
            }, completion: { animationFinished in
                self.animateCloud1()
        })
    }

The result of this code is a UIImageView (cloud1) moving from left to right across the screen. On each pass, it's y position is bein g changed randomly.

The problem is that while this animation is going on, I cannot move focus to one of the UIButtons on the screen ina predicatable manner. It seems that the UIImageView has focus and as a result no direction that I swipe in finds anything else to focus on.

Of even greater issue is the fact that whenever I am able to focus on one of the UIButtons, the UIImageView that is animating disappears as soon as the focus changes to one of the buttons.

In case it is relevant, I am changing the image of the UIButton receiving focus as follows:

    override func didUpdateFocusInContext(context: UIFocusUpdateContext, withAnimationCoordinator coordinator: UIFocusAnimationCoordinator) {
        if (context.nextFocusedView == self) {
            //Handle losing focus
            if (self.tag == 0) {
                self.setImage(UIImage(named: "butUnfocused"), forState:UIControlState.Normal )
            }
        else {
            //Handle getting focus
            if (self.tag == 0) {
                self.setImage(UIImage(named: "butFocused"), forState:UIControlState.Normal )
            }

Any thoughts on what is going on would be greatly appreciated!