How can I accurately detect if a link is clicked inside UILabels in Swift 4?

Question

Edit

See my answer for a full working solution:

I managed to solve this myself by using a UITextView instead of a UILabel

Answer 1

I managed to solve this by using a UITextView instead of a UILabel. I originally, didn't want to use a UITextView because I need the element to behave like a UILabel and a UITextView can cause issues with scrolling and it's intended use, is to be editable text. The following class I wrote makes a UITextView behave like a UILabel but with fully accurate click detection and no scrolling issues:

import UIKit

class ClickableLabelTextView: UITextView {
    var delegate: DelegateForClickEvent?
    var ranges:[(start: Int, end: Int)] = []
    var page: String = ""
    var paragraph: Int?
    var clickedLink: (() -> Void)?
    var pressedTime: Int?
    var startTime: TimeInterval?

    override func awakeFromNib() {
        super.awakeFromNib()
        self.textContainerInset = UIEdgeInsets.zero
        self.textContainer.lineFragmentPadding = 0
        self.delaysContentTouches = true
        self.isEditable = false
        self.isUserInteractionEnabled = true
        self.isSelectable = false
    }

    override func touchesBegan(_ touches: Set, with event: UIEvent?) {
        startTime = Date().timeIntervalSinceReferenceDate
    }

    override func touchesEnded(_ touches: Set, with event: UIEvent?) {
        if let clickedLink = clickedLink {
            if let startTime = startTime {
                self.startTime = nil
                if (Date().timeIntervalSinceReferenceDate - startTime <= 0.2) {
                    clickedLink()
                }
            }
        }
    }

    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        var location = point
        location.x -= self.textContainerInset.left
        location.y -= self.textContainerInset.top
        if location.x > 0 && location.y > 0 {
            let index = self.layoutManager.characterIndex(for: location, in: self.textContainer, fractionOfDistanceBetweenInsertionPoints: nil)
            var count = 0
            for range in ranges {
                if index >= range.start && index < range.end {
                    clickedLink = {
                        self.delegate?.clickedLink(page: self.page, paragraph: self.paragraph, linkNo: count)
                    }
                    return self
                }
                count += 1
            }
        }
        clickedLink = nil
        return nil
    }
}

The function hitTest get's called multiple times but that never causes a problem, as clickedLink() will only ever get called once per click. I tried disabling isUserInteractionEnabled for different views but didn't that didn't help and was unnecessary.

To use the class, simply add it to your UITextView. If you're using autoLayout in the Xcode editor, then disable Scrolling Enabled for the UITextView in the editor to avoid layout warnings.

In the Swift file that contains the code to go with your xib file (in my case a class for a UITableViewCell, you need to set the following variables for your clickable textView:

• ranges - the start and end index of every clickable link with the UITextView
• page - a String to identify the page or view that contains the the UITextView
• paragraph - If you have multiple clickable UITextView, assign each one with an number
• delegate - to delegate the click events to where ever you are able to process them.

You then need to create a protocol for your delegate:

protocol DelegateName {
    func clickedLink(page: String, paragraph: Int?, linkNo: Int?)
}

The variables passed into clickedLink give you all the information you need to know which link has been clicked.