pulsing animation. Put two UIImageViews on a view for low and highlighted. Animate the highlighted for pulsing. To stop animation remove animation from layer. Needs QuartzCore.Framework.

gistfile1.m

- (void)startAnimation
{
    self.imageViewHigh.hidden = NO; 
    CABasicAnimation *theAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
    theAnimation.duration = 1.0f;
    theAnimation.repeatCount = HUGE_VALF;
    theAnimation.autoreverses = YES;
    theAnimation.fromValue = [NSNumber numberWithFloat:0.0f];
    theAnimation.toValue = [NSNumber numberWithFloat:1.0f];
    [self.imageViewHigh.layer addAnimation:theAnimation forKey:@"animateOpacity"];
}