Character index at touch point for UILabel

Question

For a UILabel, I\'d like to find out which character index is at specific point received from a touch event. I\'d like to solve this problem for iOS 7 using Tex

Answer 1

Swift 5

 extension UITapGestureRecognizer {

 func didTapAttributedTextInLabel(label: UILabel, inRange targetRange: NSRange) -> Bool {
    // Create instances of NSLayoutManager, NSTextContainer and NSTextStorage
    let layoutManager = NSLayoutManager()
    let textContainer = NSTextContainer(size: CGSize.zero)
    let textStorage = NSTextStorage(attributedString: label.attributedText!)

    // Configure layoutManager and textStorage
    layoutManager.addTextContainer(textContainer)
    textStorage.addLayoutManager(layoutManager)

    // Configure textContainer
    textContainer.lineFragmentPadding = 0.0
    textContainer.lineBreakMode = label.lineBreakMode
    textContainer.maximumNumberOfLines = label.numberOfLines
    let labelSize = label.bounds.size
    textContainer.size = labelSize

    // Find the tapped character location and compare it to the specified range
    let locationOfTouchInLabel = self.location(in: label)
    let textBoundingBox = layoutManager.usedRect(for: textContainer)
    let textContainerOffset = CGPoint(x: (labelSize.width - textBoundingBox.size.width) * 0.5 - textBoundingBox.origin.x,
                                      y: (labelSize.height - textBoundingBox.size.height) * 0.5 - textBoundingBox.origin.y);
    let locationOfTouchInTextContainer = CGPoint(x: (locationOfTouchInLabel.x - textContainerOffset.x),
                                                 y: 0 );
    // Adjust for multiple lines of text
    let lineModifier = Int(ceil(locationOfTouchInLabel.y / label.font.lineHeight)) - 1
    let rightMostFirstLinePoint = CGPoint(x: labelSize.width, y: 0)
    let charsPerLine = layoutManager.characterIndex(for: rightMostFirstLinePoint, in: textContainer, fractionOfDistanceBetweenInsertionPoints: nil)

    let indexOfCharacter = layoutManager.characterIndex(for: locationOfTouchInTextContainer, in: textContainer, fractionOfDistanceBetweenInsertionPoints: nil)
    let adjustedRange = indexOfCharacter + (lineModifier * charsPerLine)

    return NSLocationInRange(adjustedRange, targetRange)
   }

}

it works for me.