How to change color at "00" in UITextField Xcode

Question

I'd like to change the color of "00" to gray and change the color of fix "555" to make black in my UITextField. How can i do ? Thank you for your guidance.

var placeHolder = "00"

func textFieldDidBeginEditing(_ textField: UITextField) {
    if inputCoupon.text == self.placeHolder {
        inputCoupon.text = "00"
    }
}
func textFieldDidEndEditing(_ textField: UITextField) {
    if inputCoupon.text == "00" {
        textField.text = self.placeHolder
    }
}

@objc func textFieldDidChange(_ textField: UITextField) {
    let intTmp:Int = Int("\(textField.text ?? "00")") ?? 00
    sliderBarInputCoupon.setValue(Float(intTmp), animated:true)
    let setLabel:Int = Int(intTmp)
    let payCou = setLabel * 2
    let xCoupon = Double(payCou) * 0.15
    let reWard = Int(payCou) - Int(xCoupon)
    let calReward = String(reWard)
    rewardCoupon.text = "Reward :\(calReward)"
    rewardCoupon.adjustsFontSizeToFitWidth = true
}

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool{
let currentText = textField.text ?? ""
guard let stringRange = Range(range, in: currentText) else{
    return false
}
let updateText = currentText.replacingCharacters(in: stringRange, with: string)
    return updateText.count < 6
}

enter image description here

Answer 1

UITextField has an attributedText property, that can be set to any NSAttributedString with any colors you like. For example:

// Create a string:
let attribString = NSMutableAttributedString(string: "55500")

// Set the grey color to the last two characters (the black color is the default for the rest):
attribString.addAttribute(.foregroundColor, value: UIColor.gray, range: NSRange(location: 3, length: 2))

// Set the attributed string to your text field:
textField.attributedText = attribString

Here's the example from a Playground:

Answer 2

1. Create string extension for change text color

extension String

func attributedValue(_ value:String, _ color:UIColor) -> NSMutableAttributedString {
    let attributedString: NSMutableAttributedString = NSMutableAttributedString(string: self)
    attributedString.setColor(color: color, forText: value)
    return attributedString
}

2. Create NSMutableAttributedString Extension for find string range

extension NSMutableAttributedString

func setColor(color: UIColor, forText stringValue: String) {
   let range: NSRange = self.mutableString.range(of: stringValue, options: .caseInsensitive)
    self.addAttribute(NSAttributedString.Key.foregroundColor, value: color, range: range)
}

3. How to use this code ?

textfield.text = "5500"

textfield.text.attributedValue("00", UIColor.red)

Above example will change the color of the "00" string