Update CalendarViewRepresentable methods to have the same signature as corresponding CalendarViewContent methods

Sources/Public/CalendarViewRepresentable.swift

@@ -98,13 +98,13 @@ public struct CalendarViewRepresentable: UIViewRepresentable {
   fileprivate var horizontalDayMargin: CGFloat?
   fileprivate var daysOfTheWeekRowSeparatorOptions: DaysOfTheWeekRowSeparatorOptions?
 
-  fileprivate var monthHeaderItemProvider: ((Month) -> AnyCalendarItemModel)?
+  fileprivate var monthHeaderItemProvider: ((Month) -> AnyCalendarItemModel?)?
   fileprivate var dayOfWeekItemProvider: (
     (
       _ month: Month?,
       _ weekdayIndex: Int)
-      -> AnyCalendarItemModel)?
-  fileprivate var dayItemProvider: ((Day) -> AnyCalendarItemModel)?
+      -> AnyCalendarItemModel?)?
+  fileprivate var dayItemProvider: ((Day) -> AnyCalendarItemModel?)?
   fileprivate var dayBackgroundItemProvider: ((Day) -> AnyCalendarItemModel?)?
   fileprivate var monthBackgroundItemProvider: ((MonthLayoutContext) -> AnyCalendarItemModel?)?
   fileprivate var dateRangesAndItemProvider: (
@@ -322,16 +322,16 @@ extension CalendarViewRepresentable {
   /// displayed. The `CalendarItemModel`s that you return will be used to create the views for each month header in
   /// `CalendarView`.
   ///
-  /// If you don't configure your own month header item provider via this function, then a default month header item provider will be
-  /// used.
+  /// If you don't configure your own month header item provider via this function, or if the `monthHeaderItemProvider` closure
+  /// returns nil, then a default month header item provider will be used.
   ///
   /// - Parameters:
   ///   - monthHeaderItemProvider: A closure (that is retained) that returns a `CalendarItemModel` representing a month
   ///   header.
   ///   - month: The `Month` for which to provide a month header item.
   /// - Returns: A new `CalendarViewRepresentable` with a new month header item provider.
   public func monthHeaderItemProvider(
-    _ monthHeaderItemProvider: @escaping (_ month: Month) -> AnyCalendarItemModel)
+    _ monthHeaderItemProvider: @escaping (_ month: Month) -> AnyCalendarItemModel?)
     -> Self
   {
     var view = self
@@ -365,7 +365,8 @@ extension CalendarViewRepresentable {
   /// For example, for the en_US locale, 0 is Sunday, 1 is Monday, and 6 is Saturday. This will be different in some other locales. The
   /// `CalendarItemModel`s that you return will be used to create the views for each day-of-week view in `CalendarView`.
   ///
-  /// If you don't configure your own day-of-week item provider via this function, then a default day-of-week item provider will be used.
+  /// If you don't configure your own day-of-week item provider via this function, or if the `dayOfWeekItemProvider` closure
+  /// returns `nil`, then a default day-of-week item provider will be used.
   ///
   /// - Parameters:
   ///   - dayOfWeekItemProvider: A closure (that is retained) that returns a `CalendarItemModel` representing a day of the
@@ -378,7 +379,7 @@ extension CalendarViewRepresentable {
     _ dayOfWeekItemProvider: @escaping (
       _ month: Month?,
       _ weekdayIndex: Int)
-      -> AnyCalendarItemModel)
+      -> AnyCalendarItemModel?)
     -> Self
   {
     var view = self
@@ -415,15 +416,16 @@ extension CalendarViewRepresentable {
   /// view should be some kind of label that tells the user the day number of the month. You can also add other decoration, like a
   /// badge or background, by including it in the view that your `CalendarItemModel` creates.
   ///
-  /// If you don't configure your own day item provider via this function, then a default day item provider will be used.
+  /// If you don't configure your own day item provider via this function, or if the `dayItemProvider` closure
+  /// returns nil, then a default day item provider will be used.
   ///
   /// - Parameters:
   ///   - dayItemProvider: A closure (that is retained) that returns a `CalendarItemModel` representing a single day in the
   ///   calendar.
   ///   - day: The `Day` for which to provide a day item.
   /// - Returns: A new `CalendarViewRepresentable` with a new day item provider.
   public func dayItemProvider(
-    _ dayItemProvider: @escaping (_ day: Day) -> AnyCalendarItemModel)
+    _ dayItemProvider: @escaping (_ day: Day) -> AnyCalendarItemModel?)
     -> Self
   {
     var view = self

Tests/CalendarContentTests.swift

@@ -4,6 +4,8 @@
 import XCTest
 @testable import HorizonCalendar
 
+// MARK: - CalendarContentTests
+
 final class CalendarContentTests: XCTestCase {
 
   func testCanReturnNilFromCalendarContentClosures() {
@@ -67,3 +69,31 @@ final class CalendarContentTests: XCTestCase {
   }
 
 }
+
+// MARK: - CalendarContentConfigurable
+
+/// Test case demonstrating that `CalendarViewContent` and `CalendarViewRepresentable` both have the same APIs
+/// and can be abstracted behind a single protocol
+protocol CalendarContentConfigurable {
+  func monthHeaderItemProvider(
+    _ monthHeaderItemProvider: @escaping (_ month: Month) -> AnyCalendarItemModel?)
+    -> Self
+
+  func dayOfWeekItemProvider(
+    _ dayOfWeekItemProvider: @escaping (
+      _ month: Month?,
+      _ weekdayIndex: Int)
+      -> AnyCalendarItemModel?)
+    -> Self
+
+  func dayItemProvider(_ dayItemProvider: @escaping (_ day: Day) -> AnyCalendarItemModel?) -> Self
+}
+
+// MARK: - CalendarViewContent + CalendarContentConfigurable
+
+extension CalendarViewContent: CalendarContentConfigurable { }
+
+// MARK: - CalendarViewRepresentable + CalendarContentConfigurable
+
+@available(iOS 13.0, *)
+extension CalendarViewRepresentable: CalendarContentConfigurable { }