https://stackoverflow.com/questions/4201959/label-under-image-in-uibutton

button image with caption.swift

// https://stackoverflow.com/a/35277239

extension UIButton {
    
    func alignImageAndTitleVertically(padding: CGFloat = 5.0) {
        let imageSize = self.imageView!.frame.size
        let titleSize = self.titleLabel!.frame.size
        let totalHeight = imageSize.height + titleSize.height + padding
        
        self.imageEdgeInsets = UIEdgeInsets(
            top: -(totalHeight - imageSize.height),
            left: 0,
            bottom: 0,
            right: -titleSize.width
        )
        
        self.titleEdgeInsets = UIEdgeInsets(
            top: 0,
            left: -imageSize.width,
            bottom: -(totalHeight - titleSize.height),
            right: 0
        )
    }
    
}