HyperLinkTextView.swift

protocol HyperLinkTextViewDelegate: class {
    func textView(textView: UITextView, shouldInteractWith URL: URL, in characterRange: NSRange, interaction: UITextItemInteraction) -> Bool
}

/// converts text to attributedText with clickable strings
class HyperLinkTextView: UITextView, UITextViewDelegate {
    
    weak var hyperLinkTextViewDelegate: HyperLinkTextViewDelegate?
    
    var additionalAttributesForLinkText: [NSAttributedString.Key : Any] = [:]
        
    var stringAndUrl: [String: URL] = [:] {
        didSet {
            attributedText = attributedText()
        }
    }
    
    override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        commonInit()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
    }
    
    override func awakeFromNib() {
        super.awakeFromNib()
        commonInit()
    }
    
    func commonInit() {
        delegate = self
        isEditable = false
        dataDetectorTypes = [.link]
    }
    
    private func attributedText() -> NSAttributedString {
        guard let text = self.text else {
            return NSAttributedString(string: "")
        }
        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.alignment = textAlignment
        var attributedString = NSMutableAttributedString(string: text, attributes: [
            NSAttributedString.Key.foregroundColor: UIColor.primarySystemLabelColor,
            .paragraphStyle: paragraphStyle,
            .font: self.font as Any
        ])
        if let existingAttributedString = self.attributedText { //If there existing attributedText, don't apply new attributes
            attributedString = NSMutableAttributedString(attributedString: existingAttributedString)
        }
        
        for (str, url) in stringAndUrl {
            let range = (text as NSString).range(of: str)
            attributedString.addAttribute(.link, value: url, range: range)
            additionalAttributesForLinkText.forEach { (attributeName, value) in
                attributedString.addAttribute(attributeName, value: value, range: range)
            }
        }
        return attributedString
    }
    
    override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {

        guard let pos = closestPosition(to: point) else { return false }

        guard let range = tokenizer.rangeEnclosingPosition(pos, with: .character, inDirection: .layout(.left)) else { return false }

        let startIndex = offset(from: beginningOfDocument, to: range.start)

        return attributedText.attribute(.link, at: startIndex, effectiveRange: nil) != nil
    }
    
    // MARK: UITextViewDelegate
    
    func textView(_ textView: UITextView, shouldInteractWith URL: URL, in characterRange: NSRange, interaction: UITextItemInteraction) -> Bool {
        if let hyperLinkTextViewDelegate = hyperLinkTextViewDelegate {
            return hyperLinkTextViewDelegate.textView(textView: textView, shouldInteractWith: URL, in: characterRange, interaction: interaction)
        } else {
            return false
        }
    }
}