SwiftTip6.swift

protocol FormSubmitting {
  func submitForm(_ form: Form, validates: Bool, timeout: TimeInterval)
}

extension FormSubmitting {
  func submitForm(_ form: Form,
                  validates: Bool = true,
                  timeout: TimeInterval = 60) {
    self.submitForm(form, validates: validates, timeout: timeout)
  }
}

class MyObject: FormSubmitting {
  func submitForm(_ form: Form, validates: Bool, timeout: TimeInterval) {
    print(#function, validates, timeout)
  }
}

let object = MyObject()
object.submitForm(form)
// submitForm_ :validates: timeout:) true 60.0
object.submitForm(form, validates: false, timeout: 30)
// submitForm_: validates: timeout:) false 30.0