Custom page view controller

Example/Examples/PageViewController/PageViewExampleViewController.swift

@@ -0,0 +1,70 @@
+import UIKit
+import Parchment
+
+/// Parchment provides a custom `UIPageViewController` alternative
+/// if you need better delegate methods called `PageViewController`.
+class PageViewExampleViewController: UIViewController {
+  let viewControllers: [UIViewController] = [
+    ContentViewController(index: 0),
+    ContentViewController(index: 1),
+    ContentViewController(index: 2),
+    ContentViewController(index: 3),
+    ContentViewController(index: 4),
+  ]
+
+  override func viewDidLoad() {
+    let pageViewController = PageViewController()
+    pageViewController.dataSource = self
+    pageViewController.delegate = self
+    pageViewController.selectViewController(viewControllers[0], direction: .none)
+
+    addChild(pageViewController)
+    view.addSubview(pageViewController.view)
+    view.constrainToEdges(pageViewController.view)
+    pageViewController.didMove(toParent: self)
+  }
+}
+
+extension PageViewExampleViewController: PageViewControllerDataSource {
+  func pageViewController(
+    _ pageViewController: PageViewController,
+    viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
+    guard let index = viewControllers.firstIndex(of: viewController) else { return nil }
+    if index > 0 {
+      return viewControllers[index - 1]
+    }
+    return nil
+  }
+
+  func pageViewController(
+    _ pageViewController: PageViewController,
+    viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
+    guard let index = viewControllers.firstIndex(of: viewController) else { return nil }
+    if index < viewControllers.count - 1 {
+      return viewControllers[index + 1]
+    }
+    return nil
+  }
+}
+
+extension PageViewExampleViewController: PageViewControllerDelegate {
+  func pageViewController(_ pageViewController: PageViewController, willStartScrollingFrom startingViewController: UIViewController, destinationViewController: UIViewController) {
+    print("willStartScrollingFrom: ",
+          startingViewController.title ?? "",
+          destinationViewController.title ?? "")
+  }
+
+  func pageViewController(_ pageViewController: PageViewController, isScrollingFrom startingViewController: UIViewController, destinationViewController: UIViewController?, progress: CGFloat) {
+    print("isScrollingFrom: ",
+          startingViewController.title ?? "",
+          destinationViewController?.title ?? "",
+          progress)
+  }
+
+  func pageViewController(_ pageViewController: PageViewController, didFinishScrollingFrom startingViewController: UIViewController, destinationViewController: UIViewController, transitionSuccessful: Bool) {
+    print("didFinishScrollingFrom: ",
+          startingViewController.title ?? "",
+          destinationViewController.title ?? "",
+          transitionSuccessful)
+  }
+}

Example/ExamplesViewController.swift

@@ -13,6 +13,7 @@ enum Example: CaseIterable {
   case scroll
   case header
   case multipleCells
+  case pageViewController
 
   var title: String {
     switch self {
@@ -40,6 +41,8 @@ enum Example: CaseIterable {
       return "Header above menu"
     case .multipleCells:
       return "Multiple cells"
+    case .pageViewController:
+      return "PageViewController"
     }
   }
 }
@@ -118,6 +121,8 @@ final class ExamplesViewController: UITableViewController {
       return HeaderViewController(nibName: nil, bundle: nil)
     case .multipleCells:
       return MultipleCellsViewController(nibName: nil, bundle: nil)
+    case .pageViewController:
+      return PageViewExampleViewController(nibName: nil, bundle: nil)
     }
   }