vertically align text in a CATextLayer?

Question

I am working on a CATextLayer that I want to use in both Mac and iOS. Can I control the vertical alignment of the text within the layer?

In this particular case, I

Answer 1

Swift 5.3 for macOS

class VerticallyAlignedTextLayer : CATextLayer {
    /* Credit - purebreadd - 6/24/2020
        https://stackoverflow.com/questions/4765461/vertically-align-text-in-a-catextlayer
     */

    func calculateMaxLines() -> Int {
        let maxSize = CGSize(width: frame.size.width, height: frame.size.width)
        let font = NSFont(descriptor: self.font!.fontDescriptor, size: self.fontSize)
        let charSize = floor(font!.capHeight)
        let text = (self.string ?? "") as! NSString
        let textSize = text.boundingRect(with: maxSize, options: .usesLineFragmentOrigin, attributes: [NSAttributedString.Key.font: font!], context: nil)
        let linesRoundedUp = Int(floor(textSize.height/charSize))
        return linesRoundedUp
    }
        
    override func draw(in context: CGContext) {
        let height = self.bounds.size.height
        let fontSize = self.fontSize
        let lines = CGFloat(calculateMaxLines())
        let yDiff = -(height - lines * fontSize) / 2 - lines * fontSize / 6.5 // Use -(height  - lines * fontSize) / 2 - lines * fontSize / 6.5 when in non-flipped coordinates (like macOS's default)

        context.saveGState()
        context.translateBy(x: 0, y: yDiff)
        super.draw(in: context)
        context.restoreGState()
    }
}

Notice I am dividing fontSize by 6.5, which seems to work better for my application of this solution. Thanks @purebreadd!