label_tap_location.swift

extension UILabel {
    func characterIndexTapped(tap: UITapGestureRecognizer) -> Int? {
        guard attributedText != nil else { return nil }
        // Create instances for NSLayoutManager, NSTextContainer, and NSTextStorage
        let layoutManager = NSLayoutManager()
        let textContainer = NSTextContainer(size: .zero)
        let textStorage = NSTextStorage(attributedString: attributedText!)
        layoutManager.addTextContainer(textContainer)
        textStorage.addLayoutManager(layoutManager)
        textContainer.lineFragmentPadding = 0
        textContainer.lineBreakMode = lineBreakMode
        textContainer.maximumNumberOfLines = numberOfLines
        // Calculate the tap location in terms of character index
        let location = tap.location(in: self)
        let size = bounds.size
        let textBoundingBox = layoutManager.usedRect(for: textContainer)
        let textContainerOffset = CGPoint(x: (size.width - textBoundingBox.size.width) * 0.5 - textBoundingBox.origin.x, y: (size.height - textBoundingBox.size.height) * 0.5 - textBoundingBox.origin.y)
        let locationOfTouchInTextContainer = CGPoint(x: location.x - textContainerOffset.x, y: location.y - textContainerOffset.y)
        return layoutManager.characterIndex(for: locationOfTouchInTextContainer, in: textContainer, fractionOfDistanceBetweenInsertionPoints: nil)
    }
}