StoryBoard_UITestField_CaretLogic

gistfile1.txt

import UIKit

final class UnderLineTextField: UITextField {

    private var border: CALayer

    override init(frame: CGRect) {
        border = CALayer()
        super.init(frame: .zero)
    }

    required init?(coder: NSCoder) {
        border = CALayer()
        super.init(coder: coder)
    }

    func underLineTextField(height: CGFloat) {
        self.borderStyle = UITextField.BorderStyle.none
        border.frame = CGRect(x: 0, y: self.frame.height - height, width: self.frame.width, height: height)
        self.layer.addSublayer(border)
        self.addTarget(self, action: #selector(textFieldDidChange),for: UIControl.Event.editingChanged)
    }

    func addBorderBottom() { border.backgroundColor = UIColor.gray.cgColor }

    func addBorderReset() { border.backgroundColor = UIColor.blue.cgColor }

    @objc func textFieldDidChange (textFiled: UnderLineTextField) {
        guard textFiled.text?.isEmpty == false else {
            addBorderBottom()
            return
        }
        addBorderReset()
    }
}

class ViewController: UIViewController {

    @IBOutlet weak var textFieldOne: UnderLineTextField!
    @IBOutlet weak var textFieldSecound: UnderLineTextField!

    override func viewDidLoad() {
        super.viewDidLoad()

        textFieldOne.delegate = self
        textFieldSecound.delegate = self

        textFieldOne.underLineTextField(height: 1)
        textFieldOne.addBorderBottom()

        textFieldSecound.underLineTextField(height: 1)
        textFieldSecound.addBorderBottom()
    }
}

// 今フォーカスが当たっているテキストボックスからフォーカスを外す
extension ViewController: UITextFieldDelegate {
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        if textField == textFieldOne {
            textFieldOne.resignFirstResponder()
            textFieldSecound.becomeFirstResponder()
        } else {
            textFieldSecound.resignFirstResponder()
            textFieldOne.becomeFirstResponder()
        }
        return true
    }
}