CAShapeLayer *shapeLayer=[CAShapeLayer layer];
    [shapeLayer setBounds:btn.frame];
    [shapeLayer setFillColor:[[UIColor blueColor] CGColor]];
    [shapeLayer setStrokeColor:[[UIColor blackColor] CGColor]];
    [shapeLayer setLineWidth:1.0f];
    UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:btn.frame cornerRadius:0.0];
    [shapeLayer setPath:path.CGPath];
    [[btn layer] addSublayer:shapeLayer];

    if ([shapeLayer animationForKey:@"linePhase"])
        [shapeLayer removeAnimationForKey:@"linePhase"];
    else {
        CABasicAnimation *dashAnimation;
        dashAnimation = [CABasicAnimation
                         animationWithKeyPath:@"lineDashPhase"];
        [dashAnimation setFromValue:[NSNumber numberWithFloat:0.0f]];
        [dashAnimation setToValue:[NSNumber numberWithFloat:15.0f]];
        [dashAnimation setDuration:0.75f];
        [dashAnimation setRepeatCount:10000];
        [shapeLayer addAnimation:dashAnimation forKey:@"linePhase"];
    }