Use Option<T>.optional as a variable instead of a method

Author: bcylin

Source/OptionPickerControl/Option.swift

@@ -41,7 +41,7 @@ public struct Option<T: OptionDescriptive>: Equatable {
   // MARK: - Initialization
 
   /// Returns an option that displays the optional value of an `OptionDescriptive` type.
-  public static func optional() -> Option<T> {
+  public static var optional: Option<T> {
     return Option<T>()
   }
 

Source/OptionPickerControl/OptionPickerControl.swift

@@ -45,10 +45,10 @@ open class OptionPickerControl<T: OptionDescriptive>: UIControl, UIPickerViewDat
   // MARK: - Properties
 
   /// Options that shows in the `UIPickerView`.
-  public var options: [Option<T>] = [Option<T>.optional()]
+  public var options: [Option<T>] = [.optional]
 
   /// The currently selected item in the options.
-  public var selectedOption: Option<T> = Option<T>.optional() {
+  public var selectedOption: Option<T> = .optional {
     didSet {
       if hiddenTextField.isFirstResponder {
         sendActions(for: .valueChanged)