A declarative SwiftUI form validation. Clean, simple, and customizable.




Basic Setup

  // 1 
import FormValidator

// 2
class FormInfo: ObservableObject {
  @Published var firstName: String = ""
  // 3
  lazy var form = {
    FormValidation(validationType: .immediate)
  // 4
  lazy var firstNameValidation: ValidationContainer = {
    $firstName.nonEmptyValidator(form: form, errorMessage: "First name is not valid")

struct ContentView: View {
  // 5
  @ObservedObject var formInfo = FormInfo()

  var body: some View {
    TextField("First Name", text: $formInfo.firstName)
            .validation(formInfo.firstNameValidation) // 6
  1. Import FormValidator.
  2. Declare an ObservableObject for the form with any name, for example, FormInfo, LoginInfo, or any name.
  3. Declare FormValidation object and choose a validation type.
  4. Declare a ValidationContainer for the field you need to validate.
  5. In your view, declare the FormValidation object.
  6. Declare validation(formInfo.firstNameValidation) with the validation of the field.

Congratulation!! your field is now validated for you!

Inline Validation

For fast validation, you can use InlineValidator and provide your validation logic in line:

 lazy var lastNamesValidation: ValidationContainer = {
  $lastNames.inlineValidator(form: form) { value in
    // Put validation logic here

Validation Types

You can choose between 2 different validation types: FormValidation(validationType: .immediate) and FormValidation(validationType: .deffered)

  1. immediate: the validation is triggered every time the field is changed. An error
    message will be shown in case the value is invalid.
  2. deferred: in this case, the validation will be triggered manually only using FormValidation.triggerValidation()
    The error messages will be displayed only after triggering the validation manually.

Manual Validation

You can trigger the form validation any time by calling FormValidation.triggerValidation(). After the validation, each field in the form will
display error message if it's invalid.

React to Validation Change

You can react to validation change using FormValidation.$allValid and FormValidation.$validationMessages

VStack {} // parent view of the form
        .onReceive(formInfo.form.$allValid) { isValid in self.isSaveDisabled = !isValid }
        .onReceive(formInfo.form.$validationMessages) { messages in print(messages) }

:tada: Installation


Use the following entry in your Podfile:

pod 'SwiftUIFormValidator'

Then run pod install.

Swift Package Manager

Add the following as a dependency to your Package.swift:

.package(url: "https://github.com/ShabanKamell/SwiftUIFormValidator.git")

and then specify "SwiftUIFormValidator" as a dependency of the Target in which you wish to use SwiftUIFormValidator.
Here's an example PackageDescription:

// swift-tools-version:5.1
import PackageDescription

let package = Package(
        name: "MyPackage",
        products: [
                  name: "MyPackage",
                  targets: ["MyPackage"]),
        dependencies: [
          .package(url: "https://github.com/ShabanKamell/SwiftUIFormValidator")
        targets: [
                  name: "MyPackage",
                  dependencies: ["SwiftUIFormValidator"])


Accio is a dependency manager based on SwiftPM which can build frameworks for iOS/macOS/tvOS/watchOS. Therefore the integration steps of SwiftUIFormValidator are exactly the same as described above. Once your Package.swift file is configured, run accio update instead of swift package update.

Don't forget to add import FormValidator to use the framework.


Carthage users can point to this repository and use generated SwiftUIFormValidator framework.

Make the following entry in your Cartfile:

github "ShabanKamell/SwiftUIFormValidator"

Then run carthage update.

If this is your first time using Carthage in the project, you'll need to go through some additional steps as explained over at Carthage.


Validator Description
NonEmptyValidator Validates if a string is empty of blank
EmailValidator Validates if the email is valid or not.
DateValidator Validates if a date falls within after & before dates.
PatternValidator Validates if a patten is matched or not.
InlineValidator Validates if a condition is valid or not.

Custom Validators

In easy steps, you can add a custom validator:

// 1
class CountValidator: FormValidator {
  public var publisher: ValidationPublisher!
  public var subject: ValidationSubject = .init()
  public var latestValidation: Validation = .failure(message: "")
  public var onChanged: ((Validation) -> Void)? = nil

  func validate(
          value: String,
          errorMessage: @autoclosure @escaping ValidationErrorClosure
  ) -> Validation {
    guard value.count == 2 else {
      return .failure(message: errorMessage())
    return .success

// 2
public extension Published.Publisher where Value == String {
  func countValidator(
          form: FormValidation,
          errorMessage: @autoclosure @escaping ValidationErrorClosure = ""
  ) -> ValidationContainer {
    let validator = CountValidator()
    let message = errorMessage()
    return ValidationPublishers.create(
            form: form,
            validator: validator,
            for: self,
            errorMessage: !message.isEmpty ? message : "Count must be 2")
  1. Implement FormValidator protocol.
  2. Add the validator logic in an extension to Published.Publisher.

Validation Messages

You can provide a validation message for every field by providing errorMessage

$firstName.nonEmptyValidator(form: form, errorMessage: "First name is not valid")

If you don't provide a message, a default one will be used for built-in providers.
All default messages are located in DefaultValidationMessages class.

$firstName.nonEmptyValidator(form: form) // will use the default message

In this example, DefaultValidationMessages.required will be used.

Overriding Default Validation Messages

You can override the default validation messages by inheriting from DefaultValidationMessages

class ValidationMessages: DefaultValidationMessages {
  public override var required: String {
    "Required field"
  // Override any message ...

Or if you need to override all the messages, you can implement ValidationMessagesProtocol.

And provide the messages to FormValidation

FormValidation(validationType: .immediate, messages: ValidationMessages())