[iOS | Swift] TextField: 키보드 다루기 & Formatting

View Controller class

	@IBOutlet weak var priceTextField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()
        priceTextField.becomeFirstResponder()
        priceTextField.delegate = self
    }

UITextFieldDelegate (extension)

• return 시, 키보드 내리기 & cursor 비활성화

    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder()
        textField.tintColor = UIColor.clear
        return true
    }

• textfield 터치 시, cursor 활성화

    func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {
        priceTextField.tintColor = .gray
        return true
    }

• textfield 내 formatting (가격 형태)
  

	func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        
        let formatter = NumberFormatter()
        formatter.usesGroupingSeparator = true
        formatter.numberStyle = NumberFormatter.Style.decimal
        formatter.maximumFractionDigits = 0
        formatter.decimalSeparator = "."                                  // Adapt to your case
        formatter.groupingSeparator = ","                                 // Adapt to your case
        
        // The complete string if string were added at the end
        // Here we only insert figures at the end
        
        // Let us first remove extra groupingSeparator we may have introduced to find the number
        let completeString = textField.text!.replacingOccurrences(of: formatter.groupingSeparator, with: "") + string
        
        var backSpace = false
        
        if let char = string.cString(using: String.Encoding.utf8) {
            let isBackSpace = strcmp(char, "\\b")
            if (isBackSpace == -92) {
                backSpace = true
            }
        }
        if string == "" && backSpace {           // backspace inserts nothing, but we need to accept it.
            return true
        }
        if string == "-" && textField.text! == "" {  // Accept leading minus
            return true
        }
        
        guard let value = Double(completeString) else { return false } // No double ; We do not insert
        
        let formattedNumber = formatter.string(from: NSNumber(value: value)) ?? ""
        textField.text = formattedNumber // We update the textField, adding typed character
        
        return string == formatter.decimalSeparator // No need to insert the typed char: we've done just above, unless we just typed separator
    }

참고자료

• https://developer.apple.com/documentation/uikit/uitextfielddelegate
• https://jeong9216.tistory.com/86