Arrlindii

func isEmailValid(_ value: String) -> Bool {
    do {
        if try NSRegularExpression(pattern: "^[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}$", options: .caseInsensitive).firstMatch(in: value, options: [], range: NSRange(location: 0, length: value.count)) == nil {
            return false
        }
    } catch {
        return false
    }
    return true
}

Arrlindii

class Validator {
  func isEmailValid(_ value: String) -> Bool {....} 
}

Arrlindii

func validate() {
    if Validator().isEmailValid(email:emailTextField.text) {
        validatedEmail = emailTextField.text
    }else {
        showAlert(for: "Invalid Email")
    }
}

Arrlindii

struct ValidationError: Error {
    var message: String
    
    init(_ message: String) {
        self.message = message
    }
}

Arrlindii

func validatedEmail(_ value: String) throws -> String {
    do {
        if try NSRegularExpression(pattern: "^[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}$", options: .caseInsensitive).firstMatch(in: value, options: [], range: NSRange(location: 0, length: value.count)) == nil {
            throw ValidationError("Invalid e-mail Address")
        }
    } catch {
        throw ValidationError("Invalid e-mail Address")
    }
    return value
}

Arrlindii

protocol ValidatorConvertible {
    func validated(_ value: String?) throws -> String
}

enum ValidatorType {
    case email
    case password
    case username
    case projectIdentifier
    case requiredField(field: String)

Arrlindii

func validate() {
    let emailValidator = VaildatorFactory.validatorFor(type: .email)
    do {
        try emailValidator.validate(emailTextField.text)
    }catch(let error) {
        showAlert(for: (error as! ValidationError).message)
    }
    let validatedEmail = emailTextField.text!
}

Arrlindii

extension UITextField {
    func validatedText(validationType: ValidatorType) throws -> String {
        let validator = VaildatorFactory.validatorFor(type: validationType)
        return try validator.validated(self.text!)
    }
}

Arrlindii

func validate() {
    do {
        let email = try emailTextField.validatedText(validationType: ValidatorType.email)
    } catch(let error) {
        showAlert(for: (error as! ValidationError).message)
    }
}

Arrlindii

func validate() {
    do {
        let email = try emailTextField.validatedText(validationType: ValidatorType.email)
        let username = try usernameTextField.validatedText(validationType: ValidatorType.username)
        let age = try self.ageTextField.validatedText(validationType: ValidatorType.age)
        let password = try passwordTextField.validatedText(validationType: ValidatorType.password)
        let projectId = try projectIdTextField.validatedText(validationType: ValidatorType.projectIdentifier)
        let department = try self.departmentTextField.validatedText(validationType: .requiredField(field: "Department"))
        let data = RegisterData(email: email, password: password, username: username, projectID: projectId, department: department, age: Int(age)!)
        save(data)