Detecting taps on attributed text in a UITextView

Question

I have a UITextView which displays an NSAttributedString. This string contains words that I'd like to make tappable, such that when they are tapped I get called back so that I can perform an action. I realise that UITextView can detect taps on a URL and call back my delegate, but these aren't URLs.

It seems to me that with iOS7 and the power of TextKit this should now be possible, however I can't find any examples and I'm not sure where to start.

I understand that it's now possible to create custom attributes in the string (although I haven't done this yet), and perhaps these will be useful to detecting if one of the magic words has been tapped? In any case, I still don't know how to intercept that tap and detect on which word the tap occurred.

Note that iOS 6 compatibility is not required.

Answer 1

I was able to solve this pretty simply with NSLinkAttributeName

Swift 2

class MyClass: UIViewController, UITextViewDelegate {

  @IBOutlet weak var tvBottom: UITextView!

  override func viewDidLoad() {
      super.viewDidLoad()

     let attributedString = NSMutableAttributedString(string: "click me ok?")
     attributedString.addAttribute(NSLinkAttributeName, value: "cs://moreinfo", range: NSMakeRange(0, 5))
     tvBottom.attributedText = attributedString
     tvBottom.delegate = self

  }

  func textView(textView: UITextView, shouldInteractWithURL URL: NSURL, inRange characterRange: NSRange) -> Bool {
      UtilityFunctions.alert("clicked", message: "clicked")
      return false
  }

}

Answer 2

This one might work OK with short link, multilink in a textview. It work OK with iOS 6,7,8.

- (void)tappedTextView:(UITapGestureRecognizer *)tapGesture {
    if (tapGesture.state != UIGestureRecognizerStateEnded) {
        return;
    }
    UITextView *textView = (UITextView *)tapGesture.view;
    CGPoint tapLocation = [tapGesture locationInView:textView];

    NSDataDetector *detector = [NSDataDetector dataDetectorWithTypes:NSTextCheckingTypeLink|NSTextCheckingTypePhoneNumber
                                                           error:nil];
    NSArray* resultString = [detector matchesInString:self.txtMessage.text options:NSMatchingReportProgress range:NSMakeRange(0, [self.txtMessage.text length])];
    BOOL isContainLink = resultString.count > 0;

    if (isContainLink) {
        for (NSTextCheckingResult* result in  resultString) {
            CGRect linkPosition = [self frameOfTextRange:result.range inTextView:self.txtMessage];

            if(CGRectContainsPoint(linkPosition, tapLocation) == 1){
                if (result.resultType == NSTextCheckingTypePhoneNumber) {
                    NSString *phoneNumber = [@"telprompt://" stringByAppendingString:result.phoneNumber];
                    [[UIApplication sharedApplication] openURL:[NSURL URLWithString:phoneNumber]];
                }
                else if (result.resultType == NSTextCheckingTypeLink) {
                    [[UIApplication sharedApplication] openURL:result.URL];
                }
            }
        }
    }
}

 - (CGRect)frameOfTextRange:(NSRange)range inTextView:(UITextView *)textView
{
    UITextPosition *beginning = textView.beginningOfDocument;
    UITextPosition *start = [textView positionFromPosition:beginning offset:range.location];
    UITextPosition *end = [textView positionFromPosition:start offset:range.length];
    UITextRange *textRange = [textView textRangeFromPosition:start toPosition:end];
    CGRect firstRect = [textView firstRectForRange:textRange];
    CGRect newRect = [textView convertRect:firstRect fromView:textView.textInputView];
    return newRect;
}

Answer 3

With Swift 4 and iOS 11, you can create a subclass of UITextViewand override hitTest(_:with:) or point(inside:with:) with some TextKit implementation in order to make only some NSAttributedStrings in it tappable.

---

The following code shows how to create a UITextView that only reacts to taps on underlined NSAttributedStrings in it:

InteractiveUnderlinedTextView.swift

import UIKit

class InteractiveUnderlinedTextView: UITextView {

    override init(frame: CGRect, textContainer: NSTextContainer?) {
        super.init(frame: frame, textContainer: textContainer)
        configure()
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        configure()
    }

    func configure() {
        isScrollEnabled = false
        isEditable = false
        isSelectable = false
        isUserInteractionEnabled = true
    }

    override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
        let characterIndex = layoutManager.characterIndex(for: point, in: textContainer, fractionOfDistanceBetweenInsertionPoints: nil)
        guard characterIndex < textStorage.length else { return nil }
        let attributes = textStorage.attributes(at: characterIndex, effectiveRange: nil)
        return attributes[NSAttributedStringKey.underlineStyle] != nil ? self : nil
    }

    /*
    // Alternative using point(inside:with:)
    override func point(inside point: CGPoint, with event: UIEvent?) -> Bool {
        let characterIndex = layoutManager.characterIndex(for: point, in: textContainer, fractionOfDistanceBetweenInsertionPoints: nil)
        guard characterIndex < textStorage.length else { return false }
        let attributes = textStorage.attributes(at: characterIndex, effectiveRange: nil)
        return attributes[NSAttributedStringKey.underlineStyle] != nil
    }
     */

}

ViewController.swift

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let linkTextView = InteractiveUnderlinedTextView()

        let mutableAttributedString = NSMutableAttributedString(string: "Some text\n\n\n")
        let attributes = [NSAttributedStringKey.underlineStyle: NSUnderlineStyle.styleSingle.rawValue]
        let underlinedAttributedString = NSAttributedString(string: "Some other text", attributes: attributes)
        mutableAttributedString.append(underlinedAttributedString)
        linkTextView.attributedText = mutableAttributedString

        let tapGesture = UITapGestureRecognizer(target: self, action: #selector(underlinedTextTapped))
        linkTextView.addGestureRecognizer(tapGesture)

        view.addSubview(linkTextView)
        linkTextView.translatesAutoresizingMaskIntoConstraints = false
        linkTextView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        linkTextView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
        linkTextView.leadingAnchor.constraint(equalTo: view.readableContentGuide.leadingAnchor).isActive = true

    }

    @objc func underlinedTextTapped(_ sender: UITapGestureRecognizer) {
        print("Hello")
    }

}

Answer 4

Making custom link and doing what you want on the tap has become much easier with iOS 7. There is very good example at Ray Wenderlich