how to add a string after each comma in UITextfield - swift

Question

Im lookin a way to add # at the beginig of each word written in uiTextField with swift, i tryes to check using this code
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if textField.text!.first != "#" {
print(textField.text!.first)
print(textField.text!)
textField.text = ""
}
}
but the firsrt character is nil when the input on keyboard is # so what should be the way to achive this having all the words begins with # and separated by ,

Answer 1

You can make it easier checking the text after editing changed control event and clean your string when the user types a space after each word. You can subclass your UITextField and it should look something like this:
class TagsField: UITextField, UITextFieldDelegate {
override func didMoveToSuperview() {
delegate = self
keyboardType = .alphabet
autocapitalizationType = .none
autocorrectionType = .no
addTarget(self, action: #selector(editingChanged), for: .editingChanged)
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
prepareString()
if text!.hasSuffix(", #") { text!.removeLast(3) } // clean the residue on end
resignFirstResponder()
return false
}
func prepareString() {
text = text!.components(separatedBy: CharacterSet.letters.inverted) // filtering non letters and grouping words
.filter{!$0.isEmpty} // filtering empty components
.map{ "#" + $0 + ", " } // add prefix and sufix to each word and append # to the end of the string
.string + "#"
}
override func deleteBackward() {
let _ = text!.popLast() // manually pops the last character when deliting
}
#objc func editingChanged(_ textField: UITextField) {
if text!.last == " " {
prepareString()
} else if !text!.hasPrefix("#") { // check if the first word being typed has the # prefix and add it if needed.
text!.insert("#", at: text!.startIndex)
}
}
}
extension Collection where Element: StringProtocol {
var string: String {
return String(joined())
}
}