UIImageView在初始化后正在消失

我正在UIView的一个类别中尝试这段代码(在这里的答案中找到),并使用它在UITableViewCell中嵌套的UIImageView上生成一个“pop”动画。

- (void)attachPopUpAnimation
{
    CAKeyframeAnimation *animation = [CAKeyframeAnimation
       animationWithKeyPath:@"transform"];

    CATransform3D scale1 = CATransform3DMakeScale(0.5, 0.5, 1);
    CATransform3D scale2 = CATransform3DMakeScale(1.2, 1.2, 1);
    CATransform3D scale3 = CATransform3DMakeScale(0.9, 0.9, 1);
    CATransform3D scale4 = CATransform3DMakeScale(1.0, 1.0, 1);

    NSArray *frameValues = [NSArray arrayWithObjects:
       [NSValue valueWithCATransform3D:scale1],
       [NSValue valueWithCATransform3D:scale2],
       [NSValue valueWithCATransform3D:scale3],
       [NSValue valueWithCATransform3D:scale4],
       nil];
    [animation setValues:frameValues];

    NSArray *frameTimes = [NSArray arrayWithObjects:
         [NSNumber numberWithFloat:0.0],
         [NSNumber numberWithFloat:0.5],
         [NSNumber numberWithFloat:0.9],
         [NSNumber numberWithFloat:1.0],
         nil];    
    [animation setKeyTimes:frameTimes];

    animation.fillMode = kCAFillModeForwards;
    animation.removedOnCompletion = NO;
    animation.duration = 0.2;

    [self.layer addAnimation:animation forKey:@"popup"];
}

动画可以正常工作,但当它完成时,它会消失。我已经找到了这个问题的答案,但显然设置fillMode在这种情况下不起作用。