CAKeyframeAnimation scale

I wan't to resize an UIView using keyframeAnimation because it has to be synced animated with a label text as it goes down.

So I've setup the size animation

        let sizeAnimation = CAKeyframeAnimation(keyPath: "transform.scale")
        sizeAnimation.duration = 1.2

        let animationTime = TimeInterval(1.2/Float(volumeObjects.count - 1))
        // Stride is an inverted for in, it goes from volumeObjects count to 0

        var sizeAnimationValuesArray = [NSValue]()
        var keyTimes = [NSNumber]()
        var currentKeyTime: TimeInterval = 0
        for index in stride(from: volumeObjects.count - 1, to: -1, by: -1) {

            let currentPercentage = CGFloat(index)/CGFloat(volumeObjects.count)
            sizeAnimationValuesArray.append(NSValue(caTransform3D: CATransform3DMakeScale(1.0, currentPercentage, 1.0)))
            keyTimes.append(NSNumber(value: currentKeyTime))
            currentKeyTime += animationTime
        }
        sizeAnimation.values = sizeAnimationValuesArray

        self.indicatorView.layer.add(sizeAnimation, forKey: "Bottom")

But for some reason, it doesn't work, literally nothing happens

You're not actually using the keyTimes array for anything. You populated it with times, but you didn't assign it to the animation.