A nice UITextField subclass with built-in error label, floating label while editing, and underline. For Swift 3 & 4.

A UITextField subclass which:

  • has a built-in UILabel below for showing an error message
  • floats placeholder up when text is entered
  • has an underline
  • you can customize unselected/selected color for the floating placeholder
  • you can customize unselected/selected color and thickness for the underline

System requirements

  • iOS 8.0 or newer
  • Swift 4. (If you need Swift 3, use my version 0.1.6.)


class ViewController: UIViewController {
  @IBOutlet weak var emailTextField: TKFormTextField!

  override func viewDidLoad() {

    // normal UITextField properties
    self.emailTextField.placeholder = "Email"
    self.emailTextField.enablesReturnKeyAutomatically = true
    self.emailTextField.returnKeyType = .next
    self.emailTextField.clearButtonMode = .whileEditing
    self.emailTextField.placeholderFont = UIFont.systemFont(ofSize: 18)
    self.emailTextField.font = UIFont.systemFont(ofSize: 18)

    // floating placeholder title
    self.emailTextField.titleLabel.font = UIFont.systemFont(ofSize: 18)
    self.emailTextField.titleColor = UIColor.lightGray
    self.emailTextField.selectedTitleColor = UIColor.gray

    // underline
    self.emailTextField.lineColor = UIColor.gray
    self.emailTextField.selectedLineColor =
    // bottom error label
    self.emailTextField.errorLabel.font = UIFont.systemFont(ofSize: 18)
    self.emailTextField.errorColor = // this color is also used for the underline on error state

    // update error message
    // NOTE: Ideally you should show error on .editingDidEnd, and attempt to hide it on .editingChanged.
    // See TKFormTextFieldDemo.xcodeproj on how I design the validation flow.
    self.emailTextField.addTarget(self, action: #selector(updateError), for: .editingChanged)

  func updateError(textField: TKFormTextField) {
    guard let text = textField.text, !text.isEmpty else {
      textField.error = "Text is empty!" // to show error message in errorLabel
    textField.error = nil // to remove the error message


TKFormTextField is available through CocoaPods and Carthage.

CocoaPods, add this to your Podfile:

pod "TKFormTextField"

Note: To run the example project, clone the repo, and run pod install from the Example directory first.


github "hlung/TKFormTextField"


For text input forms, using alerts for showing error is too intrusive, makes user lost context of which field is wrong, and require another tap to dismiss. And you can only show one at a time. I think TKFormTextField is the answer to text input form UI.

Note that I am not using IBInspectable / IBDesignable because I feel it is slow and buggy. Moreover, since you usually have several text fields across your app, I think it is easier to customize this in code.