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
}

CodePudding user response：

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