ValidatorKit

Chainable, declarative form validation for SwiftUI — zero boilerplate.

---

What is ValidatorKit?

ValidatorKit removes the pain of writing form validation by hand. Instead of if-else chains and scattered error state, you declare your rules once and the framework handles the rest — error messages, visual feedback, submit button state, and password strength.

// Set up validators
@StateObject var emailValidator    = FieldValidator(rules: .required, .email)
@StateObject var passwordValidator = FieldValidator(rules: .required, .minLength(8), .containsNumber)

// Use ValidatedField for automatic UI
ValidatedField(title: "Email",    text: $email,    validator: emailValidator)
ValidatedField(title: "Password", text: $password, validator: passwordValidator, isSecure: true)

---

Installation

In Xcode go to File → Add Package Dependencies and paste:

https://github.com/codewithswiftly/ValidatorKit.git

Or in Package.swift:

.package(url: "https://github.com/codewithswiftly/ValidatorKit.git", from: "1.0.1")

---

How to Use

Option 1 — ValidatedField (recommended)

Drop-in replacement for TextField with built-in error UI and border feedback.

import ValidatorKit

struct SignUpView: View {

    @State private var email    = ""
    @State private var password = ""

    @StateObject var emailValidator    = FieldValidator(rules: .required, .email)
    @StateObject var passwordValidator = FieldValidator(rules: .required, .minLength(8), .containsNumber, .containsUppercase)
    @StateObject var form              = FormValidator()

    var body: some View {
        VStack(spacing: 16) {
            ValidatedField(title: "Email",    text: $email,    validator: emailValidator, keyboardType: .emailAddress)
            ValidatedField(title: "Password", text: $password, validator: passwordValidator, isSecure: true)
            PasswordStrengthView(password: $password)

            Button("Create Account") {
                if form.validateAll(fields: [
                    (email, emailValidator),
                    (password, passwordValidator)
                ]) {
                    createAccount()
                }
            }
        }
        .padding()
    }
}

Option 2 — .validate() modifier

Attach validation to any existing TextField without replacing it.

TextField("Email", text: $email)
    .padding()
    .background(Color(.systemGray6))
    .cornerRadius(10)
    .validate($email, with: emailValidator)

Option 3 — Manual validation

For full control over when validation fires.

@StateObject var emailValidator = FieldValidator(rules: .required, .email)

let isValid = emailValidator.validate(email)

if let error = emailValidator.errorMessage {
    Text(error).foregroundStyle(.red)
}

---

Built-in Rules

Rule	Shorthand	Description
RequiredRule	.required	Cannot be empty
EmailRule	.email	Must be a valid email
MinLengthRule	.minLength(8)	Minimum character count
MaxLengthRule	.maxLength(20)	Maximum character count
MatchesRule	.matches(other)	Must equal another string
ContainsNumberRule	.containsNumber	Must have at least one digit
ContainsUppercaseRule	.containsUppercase	Must have an uppercase letter
ContainsSpecialCharacterRule	.containsSpecialCharacter	Must have a symbol
PhoneNumberRule	.phoneNumber	Valid phone number format
URLRule	.url	Valid URL with scheme and host
RegexRule	.regex(pattern:message:)	Custom regex pattern
CustomRule	.custom { ... }	Closure-based one-off rule

---

Custom Rules

Inline with CustomRule

let noBadWordsRule = CustomRule { value in
    blocklist.contains(value) ? "This username is not allowed" : nil
}

let validator = FieldValidator(rules: .required, noBadWordsRule)

As a struct (reusable)

struct IndianPhoneRule: ValidationRule {
    func validate(_ value: String) -> String? {
        let regex = #"^[6-9]\d{9}$"#
        let pred  = NSPredicate(format: "SELF MATCHES %@", regex)
        return pred.evaluate(with: value) ? nil : "Enter a valid 10-digit Indian phone number"
    }
}

let validator = FieldValidator(rules: .required, IndianPhoneRule())

---

Password Strength

VStack {
    ValidatedField(title: "Password", text: $password, validator: passwordValidator, isSecure: true)
    PasswordStrengthView(password: $password)  // Shows a colour-coded bar: Weak → Fair → Strong → Very Strong
}

// Or check strength manually
let strength = PasswordStrength.evaluate("MyP@ssw0rd!")
print(strength.label)  // "Very Strong"
print(strength.color)  // .green

---

FormValidator

Validates all fields at once when the user taps Submit.

@StateObject var form = FormValidator()

Button("Submit") {
    if form.validateAll(fields: [
        (email,    emailValidator),
        (password, passwordValidator),
        (phone,    phoneValidator)
    ]) {
        submitForm()   // Only called if every field passes
    }
}
.disabled(!form.isFormValid)

---

Project Structure

ValidatorKit/
├── Sources/ValidatorKit/
│   ├── ValidationRule.swift     # Protocol + all built-in rules + shorthands
│   ├── FieldValidator.swift     # ObservableObject for a single field
│   ├── FormValidator.swift      # Coordinates validation across multiple fields
│   ├── View+Validate.swift      # .validate() modifier for existing TextFields
│   └── PasswordStrength.swift   # Strength enum + PasswordStrengthView bar
└── Tests/ValidatorKitTests/
    └── ValidatorKitTests.swift

---

Requirements

• iOS 16+
• Swift 5.9+
• Xcode 15+
• Zero dependencies — pure SwiftUI

---

License

MIT © 2026 Rahul Das Gupta

---

Show Your Support

If you found this project useful, consider giving it a ⭐️ on GitHub!