How to read size of UISlider thumb image

Question

I\'m trying to position an additional UIView centered above the thumb in a UISlider. To do this, I need the width of the thumb image. In iOS6, this works fine. I can use:

Answer 1

Here is another one that works, however it is a little "hackier" than the first one, and makes an assumption on the default thumb Image width won't change in future versions of iOS (past 11)

- (CGFloat)thumbImageWidth // default thumb image is 30 px,
{
    double imgThumbImageWidth = self.currentThumbImage.size.width;
    if (imgThumbImageWidth && imgThumbImageWidth != 0 && imgThumbImageWidth != thumbImageWidth) {
        thumbImageWidth = imgThumbImageWidth;
    }
    else if (!thumbImageWidth || thumbImageWidth == 0) { // No custom image set, use 30
        thumbImageWidth = 31;
    }
    return thumbImageWidth;
}