Merge 4.0 into main

.gitignore

@@ -1,6 +1,7 @@
 # Xcode
 #
 build/
+.build/
 *.pbxuser
 !default.pbxuser
 *.mode1v3

Example/Examples/Header/HeaderViewController.swift

@@ -10,9 +10,9 @@ import UIKit
 class HeaderPagingView: PagingView {
     static let HeaderHeight: CGFloat = 200
 
-    var headerHeightConstraint: NSLayoutConstraint?
+    var headerHeightConstraint: NSLayoutConstraint!
 
-    private lazy var headerView: UIImageView = {
+    private(set) lazy var headerView: UIImageView = {
         let view = UIImageView(image: UIImage(named: "Header"))
         view.contentMode = .scaleAspectFill
         view.clipsToBounds = true
@@ -29,7 +29,12 @@ class HeaderPagingView: PagingView {
         headerHeightConstraint = headerView.heightAnchor.constraint(
             equalToConstant: HeaderPagingView.HeaderHeight
         )
-        headerHeightConstraint?.isActive = true
+        headerHeightConstraint.isActive = true
+        headerHeightConstraint.priority = .defaultLow
+
+        let bottomConstraint = headerView.bottomAnchor.constraint(equalTo: safeAreaLayoutGuide.topAnchor)
+        bottomConstraint.isActive = true
+        bottomConstraint.priority = .defaultHigh
 
         NSLayoutConstraint.activate([
             collectionView.leadingAnchor.constraint(equalTo: leadingAnchor),
@@ -73,9 +78,8 @@ class HeaderViewController: UIViewController {
 
     private let pagingViewController = HeaderPagingViewController()
 
-    private var headerConstraint: NSLayoutConstraint {
-        let pagingView = pagingViewController.view as! HeaderPagingView
-        return pagingView.headerHeightConstraint!
+    private var pagingView: HeaderPagingView {
+        return pagingViewController.view as! HeaderPagingView
     }
 
     override func viewDidLoad() {
@@ -128,7 +132,8 @@ extension HeaderViewController: PagingViewControllerDataSource {
         let height = pagingViewController.options.menuHeight + HeaderPagingView.HeaderHeight
         let insets = UIEdgeInsets(top: height, left: 0, bottom: 0, right: 0)
         viewController.tableView.contentInset = insets
-        viewController.tableView.scrollIndicatorInsets = insets
+        viewController.tableView.scrollIndicatorInsets = UIEdgeInsets(top: height, left: 0, bottom: 0, right: 0)
+        viewController.tableView.contentOffset.y = -insets.top
 
         return viewController
     }
@@ -155,46 +160,34 @@ extension HeaderViewController: PagingViewControllerDelegate {
         }
     }
 
-    func pagingViewController(_: PagingViewController, willScrollToItem _: PagingItem, startingViewController _: UIViewController, destinationViewController: UIViewController) {
+    func pagingViewController(_: PagingViewController, isScrollingFromItem currentPagingItem: PagingItem, toItem upcomingPagingItem: PagingItem?, startingViewController: UIViewController, destinationViewController: UIViewController?, progress: CGFloat) {
         guard let destinationViewController = destinationViewController as? TableViewController else { return }
 
         // Update the content offset based on the height of the header
         // view. This ensures that the content offset is correct if you
         // swipe to a new page while the header view is hidden.
         if let scrollView = destinationViewController.tableView {
-            let offset = headerConstraint.constant + pagingViewController.options.menuHeight
+            let offset = pagingView.headerView.bounds.height + pagingViewController.options.menuHeight
             scrollView.contentOffset = CGPoint(x: 0, y: -offset)
-            updateScrollIndicatorInsets(in: scrollView)
         }
     }
 }
 
 extension HeaderViewController: UITableViewDelegate {
-    func updateScrollIndicatorInsets(in scrollView: UIScrollView) {
-        let offset = min(0, scrollView.contentOffset.y) * -1
-        let insetTop = max(pagingViewController.options.menuHeight, offset)
-        let insets = UIEdgeInsets(top: insetTop, left: 0, bottom: 0, right: 0)
-        scrollView.scrollIndicatorInsets = insets
-    }
-
     func scrollViewDidScroll(_ scrollView: UIScrollView) {
         guard scrollView.contentOffset.y < 0 else {
             // Reset the header constraint in case we scrolled so fast that
             // the height was not set to zero before the content offset
             // became negative.
-            if headerConstraint.constant > 0 {
-                headerConstraint.constant = 0
+            if pagingView.headerHeightConstraint.constant > 0 {
+                pagingView.headerHeightConstraint.constant = 0
             }
             return
         }
 
-        // Update the scroll indicator insets so they move alongside the
-        // header view when scrolling.
-        updateScrollIndicatorInsets(in: scrollView)
-
         // Update the height of the header view based on the content
         // offset of the currently selected view controller.
         let height = max(0, abs(scrollView.contentOffset.y) - pagingViewController.options.menuHeight)
-        headerConstraint.constant = height
+        pagingView.headerHeightConstraint.constant = height
     }
 }

Example/Examples/Icons/IconsViewController.swift

@@ -1,30 +1,17 @@
 import Parchment
 import UIKit
 
-struct IconItem: PagingItem, Hashable {
+struct IconItem: PagingItem, PagingIndexable, Hashable {
+    let identifier: Int
     let icon: String
     let index: Int
     let image: UIImage?
 
     init(icon: String, index: Int) {
+        self.identifier = icon.hashValue
         self.icon = icon
         self.index = index
-        image = UIImage(named: icon)
-    }
-
-    /// By default, isBefore is implemented when the PagingItem conforms
-    /// to Comparable, but in this case we want a custom implementation
-    /// where we also compare IconItem with PagingIndexItem. This
-    /// ensures that we animate the page transition in the correct
-    /// direction when selecting items.
-    func isBefore(item: PagingItem) -> Bool {
-        if let item = item as? PagingIndexItem {
-            return index < item.index
-        } else if let item = item as? Self {
-            return index < item.index
-        } else {
-            return false
-        }
+        self.image = UIImage(named: icon)
     }
 }
 
@@ -64,7 +51,7 @@ class IconsViewController: UIViewController {
         pagingViewController.select(pagingItem: IconItem(icon: icons[0], index: 0))
 
         // Add the paging view controller as a child view controller
-        // and contrain it to all edges.
+        // and constrain it to all edges.
         addChild(pagingViewController)
         view.addSubview(pagingViewController.view)
         view.constrainToEdges(pagingViewController.view)

Example/Examples/Images/UnsplashViewController.swift

@@ -34,12 +34,12 @@ class ImagePagingView: PagingView {
         NSLayoutConstraint.activate([
             collectionView.leadingAnchor.constraint(equalTo: leadingAnchor),
             collectionView.trailingAnchor.constraint(equalTo: trailingAnchor),
-            collectionView.topAnchor.constraint(equalTo: topAnchor),
+            collectionView.topAnchor.constraint(equalTo: safeAreaLayoutGuide.topAnchor),
 
             pageView.leadingAnchor.constraint(equalTo: leadingAnchor),
             pageView.trailingAnchor.constraint(equalTo: trailingAnchor),
             pageView.bottomAnchor.constraint(equalTo: bottomAnchor),
-            pageView.topAnchor.constraint(equalTo: topAnchor),
+            pageView.topAnchor.constraint(equalTo: safeAreaLayoutGuide.topAnchor),
         ])
     }
 }

Example/Examples/LargeTitles/LargeTitlesViewController.swift

@@ -58,27 +58,8 @@ class LargeTitlesViewController: UIViewController {
         // Tell the navigation bar that we want to have large titles
         navigationController.navigationBar.prefersLargeTitles = true
 
-        // Customize the menu to match the navigation bar color
-        let blue = UIColor(red: 3 / 255, green: 125 / 255, blue: 233 / 255, alpha: 1)
-
-        if #available(iOS 13.0, *) {
-            let appearance = UINavigationBarAppearance()
-            appearance.backgroundColor = blue
-            appearance.titleTextAttributes = [.foregroundColor: UIColor.white]
-            appearance.largeTitleTextAttributes = [.foregroundColor: UIColor.white]
-
-            UINavigationBar.appearance().tintColor = .white
-            UINavigationBar.appearance().standardAppearance = appearance
-            UINavigationBar.appearance().compactAppearance = appearance
-            UINavigationBar.appearance().scrollEdgeAppearance = appearance
-        } else {
-            UINavigationBar.appearance().tintColor = .white
-            UINavigationBar.appearance().barTintColor = blue
-            UINavigationBar.appearance().isTranslucent = false
-        }
-
         view.backgroundColor = .white
-        pagingViewController.menuBackgroundColor = blue
+        pagingViewController.menuBackgroundColor = .systemBlue
         pagingViewController.menuItemSize = .fixed(width: 150, height: 30)
         pagingViewController.textColor = UIColor.white.withAlphaComponent(0.7)
         pagingViewController.selectedTextColor = UIColor.white
@@ -148,6 +129,7 @@ extension LargeTitlesViewController: PagingViewControllerDataSource {
         let insets = UIEdgeInsets(top: pagingViewController.options.menuItemSize.height, left: 0, bottom: 0, right: 0)
         viewController.tableView.scrollIndicatorInsets = insets
         viewController.tableView.contentInset = insets
+        viewController.tableView.contentOffset.y = -insets.top
         return viewController
     }
 

Example/Examples/NavigationBar/NavigationBarViewController.swift

@@ -45,14 +45,14 @@ class NavigationBarViewController: UIViewController {
         pagingViewController.selectedTextColor = .white
 
         // Make sure you add the PagingViewController as a child view
-        // controller and contrain it to the edges of the view.
+        // controller and constrain it to the edges of the view.
         addChild(pagingViewController)
         view.addSubview(pagingViewController.view)
         view.constrainToEdges(pagingViewController.view)
         pagingViewController.didMove(toParent: self)
 
         // Set the menu view as the title view on the navigation bar. This
-        // will remove the menu view from the view hierachy and put it
+        // will remove the menu view from the view hierarchy and put it
         // into the navigation bar.
         navigationItem.titleView = pagingViewController.collectionView
     }

Example/Examples/Scroll/ScrollViewController.swift

@@ -49,19 +49,21 @@ class ScrollViewController: UIViewController {
         super.viewDidLoad()
 
         // Add the paging view controller as a child view controller and
-        // contrain it to all edges.
+        // constrain it to all edges.
         addChild(pagingViewController)
         view.addSubview(pagingViewController.view)
         view.constrainToEdges(pagingViewController.view)
         pagingViewController.didMove(toParent: self)
 
+        // Prevent the menu from showing when scrolled out of view.
+        pagingViewController.view.clipsToBounds = true
+
         // Set our data source and delegate.
         pagingViewController.dataSource = self
         pagingViewController.delegate = self
     }
 
-    /// Calculate the menu offset based on the content offset of the
-    /// scroll view.
+    /// Calculate the menu offset based on the content offset of the scroll view.
     private func menuOffset(for scrollView: UIScrollView) -> CGFloat {
         return min(pagingViewController.options.menuHeight, max(0, scrollView.contentOffset.y))
     }
@@ -80,6 +82,9 @@ extension ScrollViewController: PagingViewControllerDataSource {
         // Set delegate so that we can listen to scroll events.
         viewController.tableView.delegate = self
 
+        // Ensure that the scroll view is scroll to the top.
+        viewController.tableView.contentOffset.y = -insets.top
+
         return viewController
     }
 
@@ -94,8 +99,13 @@ extension ScrollViewController: PagingViewControllerDataSource {
 
 extension ScrollViewController: UITableViewDelegate {
     func scrollViewDidScroll(_ scrollView: UIScrollView) {
-        // Offset the menu view based on the content offset of the
-        // scroll view.
+        // Only update the menu when the currently selected view is scrolled.
+        guard
+            let selectedViewController = pagingViewController.pageViewController.selectedViewController as? TableViewController,
+            selectedViewController.tableView === scrollView
+        else { return }
+
+        // Offset the menu view based on the content offset of the scroll view.
         if let menuView = pagingViewController.view as? ScrollPagingView {
             menuView.menuTopConstraint?.constant = -menuOffset(for: scrollView)
         }
@@ -116,6 +126,11 @@ extension ScrollViewController: PagingViewControllerDelegate {
         let to = menuOffset(for: destinationViewController.tableView)
         let offset = ((to - from) * abs(progress)) + from
 
+        // Reset the content offset when scrolling to a new page. You
+        // could also remove this, and it will hide the menu when
+        // swiping back to the previous page.
+        destinationViewController.tableView.contentOffset.y = -pagingViewController.options.menuHeight
+
         menuView.menuTopConstraint?.constant = -offset
     }
 }

Example/Examples/Wheel/WheelViewController.swift

@@ -0,0 +1,28 @@
+import Parchment
+import UIKit
+
+final class WheelViewController: UIViewController {
+    override func viewDidLoad() {
+        super.viewDidLoad()
+
+        let viewControllers = [
+            ContentViewController(index: 0),
+            ContentViewController(index: 1),
+            ContentViewController(index: 2),
+            ContentViewController(index: 3),
+            ContentViewController(index: 4),
+            ContentViewController(index: 5),
+            ContentViewController(index: 6),
+        ]
+
+        let pagingViewController = PagingViewController(viewControllers: viewControllers)
+        pagingViewController.menuInteraction = .wheel
+        pagingViewController.selectedScrollPosition = .center
+        pagingViewController.menuItemSize = .fixed(width: 100, height: 60)
+
+        addChild(pagingViewController)
+        view.addSubview(pagingViewController.view)
+        view.constrainToEdges(pagingViewController.view)
+        pagingViewController.didMove(toParent: self)
+    }
+}

Example/ExamplesViewController.swift

@@ -5,6 +5,7 @@ enum Example: CaseIterable {
     case selfSizing
     case calendar
     case sizeDelegate
+    case wheel
     case images
     case icons
     case storyboard
@@ -25,6 +26,8 @@ enum Example: CaseIterable {
             return "Calendar"
         case .sizeDelegate:
             return "Size delegate"
+        case .wheel:
+            return "Wheel"
         case .images:
             return "Images"
         case .icons:
@@ -82,7 +85,7 @@ final class ExamplesViewController: UITableViewController {
 
         switch example {
         case .largeTitles:
-            let navigationController = UINavigationController(rootViewController: viewController)
+            let navigationController = NavigationController(rootViewController: viewController)
             navigationController.modalPresentationStyle = .fullScreen
             viewController.navigationItem.rightBarButtonItem = UIBarButtonItem(
                 barButtonSystemItem: .done,
@@ -106,6 +109,8 @@ final class ExamplesViewController: UITableViewController {
             return SelfSizingViewController()
         case .sizeDelegate:
             return SizeDelegateViewController(nibName: nil, bundle: nil)
+        case .wheel:
+            return WheelViewController()
         case .images:
             return UnsplashViewController(nibName: nil, bundle: nil)
         case .icons:
@@ -131,3 +136,32 @@ final class ExamplesViewController: UITableViewController {
         dismiss(animated: true)
     }
 }
+
+final class NavigationController: UINavigationController {
+    override var preferredStatusBarStyle: UIStatusBarStyle {
+        return .lightContent
+    }
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        let appearance = UINavigationBarAppearance()
+        appearance.backgroundColor = .systemBlue
+        appearance.titleTextAttributes = [.foregroundColor: UIColor.white]
+        appearance.largeTitleTextAttributes = [.foregroundColor: UIColor.white]
+        navigationBar.tintColor = .white
+        navigationBar.standardAppearance = appearance
+        navigationBar.compactAppearance = appearance
+        navigationBar.scrollEdgeAppearance = appearance
+    }
+
+    // For debugging purposes. Adds a hook to push a new view
+    // controller to debug navigation controller related issues.
+    override func motionBegan(_ motion: UIEvent.EventSubtype, with event: UIEvent?) {
+        if motion == .motionShake {
+            let viewController = UIViewController()
+            viewController.title = "Page"
+            viewController.view.backgroundColor = .white
+            pushViewController(viewController, animated: true)
+        }
+    }
+}