Get text characters frame on UILabel - ios

Question

I've a ULabel on my view controller. So, If user draws line over the UILabel then I've to print text from the UILabel by user drawn range. This is the purpose.
My question is,
How to get character frames from the CGPoint ranges (start & end) on UILabel? I simply want to print the string as I coded.
Diagram:
Drawing:
String Range:
I don't have any clue to solve this problem. So, Please help to find the solution. Thanks in advance...
Code:
import UIKit
class ViewController: UIViewController {
let font: UIFont = UIFont.systemFont(ofSize: 16, weight: .medium)
lazy var label: UILabel = {
let label = UILabel()
label.text = "The orange is the fruit of various citrus"
label.font = font
label.textAlignment = .left
view.addSubview(label)
label.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
label.leftAnchor.constraint(equalTo: view.leftAnchor),
label.rightAnchor.constraint(equalTo: view.rightAnchor),
label.centerYAnchor.constraint(equalTo: view.centerYAnchor),
])
return label
}()
override func viewDidLoad() {
super.viewDidLoad()
label.textColor = .white
label.backgroundColor = .black
let button = UIButton(frame: .init(x: (view.frame.width/2)-30, y: 80, width: 60, height: 40))
button.backgroundColor = .gray
button.setTitle("Print", for: .normal)
button.addTarget(self, action: #selector(actionButton), for: .touchUpInside)
view.addSubview(button)
}
#objc func actionButton(){
//Any demo points.
let p1 = CGPoint.zero
let p2 = CGPoint(x: 70, y: 0)
print("String: ")
}
}

Answer 1

Try this in Swift Playground
import UIKit
import PlaygroundSupport
class MyViewController : UIViewController {
override func loadView() {
let view = UIView()
view.backgroundColor = .white
let label = UILabelExtended()
label.frame = view.bounds
label.autoresizingMask = [.flexibleWidth, .flexibleHeight]
label.numberOfLines = 0
label.text = "Lorem ipsum, or lipsum as it is sometimes known, is dummy text used in laying out print, graphic or web designs. The passage is attributed to an unknown typesetter in the 15th century who is thought to have scrambled parts of Cicero's De Finibus Bonorum et Malorum for use in a type specimen book."
label.textColor = .black
view.addSubview(label)
self.view = view
}
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()
class UILabelExtended: UILabel {
let layoutManager = NSLayoutManager()
let textContainer = NSTextContainer(size: .zero)
var textStorage = NSTextStorage()
lazy var gesture = TouchGestureRecognizer(target: self, action: #selector(onSwipe(gesture:)))
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
commonInit()
}
func commonInit() {
isUserInteractionEnabled = true
addGestureRecognizer(gesture)
}
override var text: String? {
get {
return super.attributedText?.string
}
set {
let attrs: [NSAttributedString.Key : Any] = [.font: font!]
attributedText = NSAttributedString(string: newValue ?? "", attributes: attrs)
updateTextContainer()
}
}
var startIndex = -1
var endIndex = -1
var startPoint = CGPoint.zero
var endPoint = CGPoint.zero
#objc func onSwipe(gesture: UIGestureRecognizer) {
switch gesture.state {
case .began:
updateBoundingBox()
let start = getTextIndexFrom(point: gesture.location(in: self))
startIndex = start.0
startPoint = start.1
case .changed:
let end = getTextIndexFrom(point: gesture.location(in: self))
endIndex = end.0
endPoint = end.1
if let text = attributedText?.string, startIndex > -1 {
if startIndex > endIndex { swap(&startIndex, &endIndex) }
let s = text.index(text.startIndex, offsetBy: startIndex)
let e = text.index(text.startIndex, offsetBy: endIndex)
print(startPoint, endPoint, text[s...e])
}
default:
break
}
setNeedsDisplay()
}
var textBoundingBox: CGRect = .zero
private func updateBoundingBox() {
textBoundingBox = layoutManager.usedRect(for: textContainer)
textBoundingBox.origin = CGPoint(x: bounds.midX - textBoundingBox.size.width / 2, y: bounds.midY - textBoundingBox.size.height / 2)
}
private func getTextIndexFrom(point: CGPoint) -> (Int, CGPoint) {
let touchPoint = CGPoint(x: point.x - textBoundingBox.origin.x, y: point.y - textBoundingBox.origin.y)
let index = layoutManager.characterIndex(for: touchPoint, in: textContainer, fractionOfDistanceBetweenInsertionPoints: nil)
return (index, touchPoint)
}
private func updateTextContainer() {
textStorage = .init(attributedString: attributedText!)
layoutManager.addTextContainer(textContainer)
textStorage.addLayoutManager(layoutManager)
textContainer.lineFragmentPadding = 0.0
textContainer.lineBreakMode = lineBreakMode
textContainer.maximumNumberOfLines = numberOfLines
}
override func layoutSubviews() {
super.layoutSubviews()
textContainer.size = bounds.size
}
override func draw(_ rect: CGRect) {
super.draw(rect)
if let context = UIGraphicsGetCurrentContext() {
context.setStrokeColor(UIColor.red.cgColor)
context.setLineWidth(2)
context.move(to: startPoint)
context.addLine(to: endPoint)
context.addRect(textBoundingBox)
context.strokePath()
}
}
}
class TouchGestureRecognizer: UIGestureRecognizer, UIGestureRecognizerDelegate {
override init(target: Any?, action: Selector?) {
super.init(target: target, action: action)
delegate = self
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
state = .began
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
state = .changed
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
state = .ended
}
override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent) {
state = .cancelled
}
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
return !(otherGestureRecognizer is TouchGestureRecognizer)
}
}