feat: add base64 validation rule

Examples/Core/Content.playground/Contents.swift

@@ -5,7 +5,7 @@
 
 import ValidatorCore
 
-// 1. LengthValidationRule - validates string length
+/// 1. LengthValidationRule - validates string length
 let lengthRule = LengthValidationRule(min: 3, max: 20, error: "Length must be 3-20 characters")
 
 let shortString = "ab"
@@ -18,7 +18,7 @@ print("'\(validString)' is valid: \(lengthRule.validate(input: validString))") /
 print("'\(longString)' is valid: \(lengthRule.validate(input: longString))") // false
 print()
 
-// 2. NonEmptyValidationRule - checks if string is not empty
+/// 2. NonEmptyValidationRule - checks if string is not empty
 let nonEmptyRule = NonEmptyValidationRule(error: "Field is required")
 
 let emptyString = ""
@@ -31,7 +31,7 @@ print("'\(whitespaceString)' is valid: \(nonEmptyRule.validate(input: whitespace
 print("'\(filledString)' is valid: \(nonEmptyRule.validate(input: filledString))") // true
 print()
 
-// 3. PrefixValidationRule - validates string prefix
+/// 3. PrefixValidationRule - validates string prefix
 let prefixRule = PrefixValidationRule(prefix: "https://", error: "URL must start with https://")
 
 let httpURL = "http://example.com"
@@ -44,7 +44,7 @@ print("'\(httpsURL)' is valid: \(prefixRule.validate(input: httpsURL))") // true
 print("'\(noProtocol)' is valid: \(prefixRule.validate(input: noProtocol))") // false
 print()
 
-// 4. SuffixValidationRule - validates string suffix
+/// 4. SuffixValidationRule - validates string suffix
 let suffixRule = SuffixValidationRule(suffix: ".com", error: "Domain must end with .com")
 
 let comDomain = "example.com"
@@ -57,7 +57,7 @@ print("'\(orgDomain)' is valid: \(suffixRule.validate(input: orgDomain))") // fa
 print("'\(noDomain)' is valid: \(suffixRule.validate(input: noDomain))") // false
 print()
 
-// 5. RegexValidationRule - validates using regular expression
+/// 5. RegexValidationRule - validates using regular expression
 let phoneRule = RegexValidationRule(pattern: "^\\d{3}-\\d{4}$", error: "Invalid phone format")
 
 let validPhone = "123-4567"
@@ -70,7 +70,7 @@ print("'\(invalidPhone1)' is valid: \(phoneRule.validate(input: invalidPhone1))"
 print("'\(invalidPhone2)' is valid: \(phoneRule.validate(input: invalidPhone2))") // false
 print()
 
-// 6. URLValidationRule - validates URL format
+/// 6. URLValidationRule - validates URL format
 let urlRule = URLValidationRule(error: "Please enter a valid URL")
 
 let validURL = "https://www.apple.com"
@@ -83,7 +83,7 @@ print("'\(invalidURL)' is valid: \(urlRule.validate(input: invalidURL))") // fal
 print("'\(localURL)' is valid: \(urlRule.validate(input: localURL))") // true
 print()
 
-// 7. CreditCardValidationRule - validates credit card number (Luhn algorithm)
+/// 7. CreditCardValidationRule - validates credit card number (Luhn algorithm)
 let cardRule = CreditCardValidationRule(error: "Invalid card number")
 
 let validCard = "4532015112830366" // Valid Visa test number
@@ -96,7 +96,7 @@ print("'\(invalidCard)' is valid: \(cardRule.validate(input: invalidCard))") //
 print("'\(shortCard)' is valid: \(cardRule.validate(input: shortCard))") // false
 print()
 
-// 8. EmailValidationRule - validates email format
+/// 8. EmailValidationRule - validates email format
 let emailRule = EmailValidationRule(error: "Please enter a valid email")
 
 let validEmail = "user@example.com"
@@ -109,7 +109,7 @@ print("'\(invalidEmail1)' is valid: \(emailRule.validate(input: invalidEmail1))"
 print("'\(invalidEmail2)' is valid: \(emailRule.validate(input: invalidEmail2))") // false
 print()
 
-// 9. CharactersValidationRule - validates allowed characters
+/// 9. CharactersValidationRule - validates allowed characters
 let lettersRule = CharactersValidationRule(characterSet: .letters, error: "Invalid characters")
 
 let onlyLetters = "HelloWorld"
@@ -122,7 +122,7 @@ print("'\(withNumbers)' is valid: \(lettersRule.validate(input: withNumbers))")
 print("'\(withSpaces)' is valid: \(lettersRule.validate(input: withSpaces))") // false
 print()
 
-// 10. NilValidationRule - validates that value is nil
+/// 10. NilValidationRule - validates that value is nil
 let nilRule = NilValidationRule<String>(error: "Value must be nil")
 
 let nilValue: String? = nil

Examples/Core/PlaygroundDependencies/Tests/PlaygroundDependenciesTests/PlaygroundDependenciesTests.swift

@@ -6,6 +6,6 @@
 @testable import PlaygroundDependencies
 import Testing
 
-@Test func example() async throws {
+@Test func example() {
     // Write your test here and use APIs like `#expect(...)` to check expected conditions.
 }

Examples/UIKit/UIKitExample/ViewControllers/LoginTextFieldExampleViewController.swift

@@ -10,7 +10,7 @@ import ValidatorUI
 final class LoginTextFieldExampleViewController: UIViewController {
     // MARK: - Properties
 
-    // UI
+    /// UI
     private let scrollView: UIScrollView = {
         let scrollView = UIScrollView()
         scrollView.translatesAutoresizingMaskIntoConstraints = false
@@ -67,7 +67,7 @@ final class LoginTextFieldExampleViewController: UIViewController {
         return stackView
     }()
 
-    // Private properties
+    /// Private properties
     private var isValid: Bool {
         [firstNameTextField, lastNameTextField, emailTextField]
             .allSatisfy { $0.validationResult == .valid }

README.md

@@ -317,6 +317,7 @@ struct RegistrationView: View {
 | `IBANValidationRule` | Validates that a string is a valid IBAN (International Bank Account Number) | `IBANValidationRule(error: "Invalid IBAN")`
 | `IPAddressValidationRule` | Validates that a string is a valid IPv4 or IPv6 address | `IPAddressValidationRule(version: .v4, error: ValidationError("Invalid IPv4"))`
 | `PostalCodeValidationRule` | Validates postal/ZIP codes for different countries | `PostalCodeValidationRule(country: .uk, error: "Invalid post code")`
+| `Base64ValidationRule` | | `Base64ValidationRule(error: "The input is not valid Base64.")`
 
 ## Custom Validators
 

Sources/ValidatorCore/Classes/Extensions/String+IValidationError.swift

@@ -22,5 +22,7 @@ import Foundation
 /// ```
 extension String: IValidationError {
     /// Returns the string itself as the error message.
-    public var message: String { self }
+    public var message: String {
+        self
+    }
 }

Sources/ValidatorCore/Classes/Rules/Base64ValidationRule.swift

@@ -0,0 +1,52 @@
+//
+// Validator
+// Copyright © 2026 Space Code. All rights reserved.
+//
+
+import Foundation
+
+/// Validates that a string represents valid Base64-encoded data.
+///
+/// # Example:
+/// ```swift
+/// let rule = Base64ValidationRule(error: "Invalid Base64")
+/// rule.validate(input: "SGVsbG8gV29ybGQ=") // true
+/// rule.validate(input: "not_base64!") // false
+/// ```
+public struct Base64ValidationRule: IValidationRule {
+    // MARK: Types
+
+    public typealias Input = String
+
+    // MARK: Properties
+
+    /// The validation error returned if the input is not valid Base64.
+    public let error: IValidationError
+
+    // MARK: Initialization
+
+    /// Initializes a Base64 validation rule.
+    ///
+    /// - Parameter error: The validation error returned if input fails validation.
+    public init(error: IValidationError) {
+        self.error = error
+    }
+
+    // MARK: IValidationRule
+
+    public func validate(input: String) -> Bool {
+        guard !input.isEmpty else { return false }
+
+        let cleanedInput = input.replacingOccurrences(of: "\\s", with: "", options: .regularExpression)
+
+        guard !cleanedInput.isEmpty else { return false }
+
+        guard cleanedInput.count.isMultiple(of: 4) else { return false }
+
+        guard Data(base64Encoded: cleanedInput) != nil else { return false }
+
+        let base64Pattern = "^[A-Za-z0-9+/]*={0,2}$"
+        let predicate = NSPredicate(format: "SELF MATCHES %@", base64Pattern)
+        return predicate.evaluate(with: cleanedInput)
+    }
+}

Sources/ValidatorCore/Classes/Rules/URLValidationRule.swift

@@ -5,14 +5,14 @@
 
 import Foundation
 
-/// Validates that a string represents a valid URL.
-///
-/// # Example:
-/// ```swift
-/// let rule = URLValidationRule(error: "Invalid URL")
-/// rule.validate(input: "https://example.com") // true
-/// rule.validate(input: "not_a_url") // false
-/// ```
+// Validates that a string represents a valid URL.
+//
+// # Example:
+// ```swift
+// let rule = URLValidationRule(error: "Invalid URL")
+// rule.validate(input: "https://example.com") // true
+// rule.validate(input: "not_a_url") // false
+// ```
 
 public struct URLValidationRule: IValidationRule {
     // MARK: Types

Sources/ValidatorCore/Validator.docc/Overview.md

@@ -40,6 +40,7 @@ ValidatorCore contains all core validation rules, utilities, and mechanisms for
 - ``IBANValidationRule``
 - ``IPAddressValidationRule``
 - ``PostalCodeValidationRule``
+- ``Base64ValidationRule``
 
 ### Articles
 

Sources/ValidatorUI/Classes/AppKit/Extensions/NSTextField+Validation.swift

@@ -9,7 +9,9 @@
     extension NSTextField: IUIValidatable {
         /// The value of the text field to validate.
         /// Returns an empty string if `text` is nil.
-        public var inputValue: String { stringValue }
+        public var inputValue: String {
+            stringValue
+        }
 
         /// The type of input for validation.
         public typealias Input = String

Sources/ValidatorUI/Classes/UIKit/Extensions/UITextField+Validation.swift

@@ -9,7 +9,9 @@
     extension UITextField: IUIValidatable {
         /// The value of the text field to validate.
         /// Returns an empty string if `text` is nil.
-        public var inputValue: String { text ?? "" }
+        public var inputValue: String {
+            text ?? ""
+        }
 
         /// The type of input for validation.
         public typealias Input = String

Sources/ValidatorUI/Classes/UIKit/Extensions/UITextView+Validation.swift

@@ -9,7 +9,9 @@
     extension UITextView: IUIValidatable {
         /// The value of the text view to validate.
         /// Returns an empty string if `text` is nil.
-        public var inputValue: String { text ?? "" }
+        public var inputValue: String {
+            text ?? ""
+        }
 
         /// The type of input for validation.
         public typealias Input = String