Two column navigation on iPad

Tusker.xcodeproj/project.pbxproj

@@ -291,6 +291,7 @@
 		D6E77D09286D25FA00D8B732 /* TrendingHashtagCollectionViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E77D08286D25FA00D8B732 /* TrendingHashtagCollectionViewCell.swift */; };
 		D6E77D0B286D426E00D8B732 /* TrendingLinkCardCollectionViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E77D0A286D426E00D8B732 /* TrendingLinkCardCollectionViewCell.swift */; };
 		D6E77D0D286E6B7300D8B732 /* TrendingLinkCardCollectionViewCell.xib in Resources */ = {isa = PBXBuildFile; fileRef = D6E77D0C286E6B7300D8B732 /* TrendingLinkCardCollectionViewCell.xib */; };
+		D6E77D0F286F773900D8B732 /* SplitNavigationController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E77D0E286F773900D8B732 /* SplitNavigationController.swift */; };
 		D6E9CDA8281A427800BBC98E /* PostService.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E9CDA7281A427800BBC98E /* PostService.swift */; };
 		D6EAE0DB2550CC8A002DB0AC /* FocusableTextField.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6EAE0DA2550CC8A002DB0AC /* FocusableTextField.swift */; };
 		D6EBF01523C55C0900AE061B /* UIApplication+Scenes.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6EBF01423C55C0900AE061B /* UIApplication+Scenes.swift */; };
@@ -645,6 +646,7 @@
 		D6E77D08286D25FA00D8B732 /* TrendingHashtagCollectionViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TrendingHashtagCollectionViewCell.swift; sourceTree = "<group>"; };
 		D6E77D0A286D426E00D8B732 /* TrendingLinkCardCollectionViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TrendingLinkCardCollectionViewCell.swift; sourceTree = "<group>"; };
 		D6E77D0C286E6B7300D8B732 /* TrendingLinkCardCollectionViewCell.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = TrendingLinkCardCollectionViewCell.xib; sourceTree = "<group>"; };
+		D6E77D0E286F773900D8B732 /* SplitNavigationController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SplitNavigationController.swift; sourceTree = "<group>"; };
 		D6E9CDA7281A427800BBC98E /* PostService.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PostService.swift; sourceTree = "<group>"; };
 		D6EAE0DA2550CC8A002DB0AC /* FocusableTextField.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FocusableTextField.swift; sourceTree = "<group>"; };
 		D6EBF01423C55C0900AE061B /* UIApplication+Scenes.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "UIApplication+Scenes.swift"; sourceTree = "<group>"; };
@@ -1298,6 +1300,7 @@
 				D653F410267D1E32004E32B1 /* DiffableTimelineLikeTableViewController.swift */,
 				D625E4812588262A0074BB2B /* DraggableTableViewCell.swift */,
 				D693DE5623FE1A6A0061E07D /* EnhancedNavigationViewController.swift */,
+				D6E77D0E286F773900D8B732 /* SplitNavigationController.swift */,
 				D6BC8747219738E1006163F1 /* EnhancedTableViewController.swift */,
 				D693DE5823FE24300061E07D /* InteractivePushTransition.swift */,
 				D6C693FB2162FE6F007D6A6D /* LoadingViewController.swift */,
@@ -1804,6 +1807,7 @@
 				D662AEF2263A4BE10082A153 /* ComposePollView.swift in Sources */,
 				D677284A24ECBDF400C732D3 /* ComposeCurrentAccount.swift in Sources */,
 				D62D2424217ABF3F005076CC /* NSUserActivity+Extensions.swift in Sources */,
+				D6E77D0F286F773900D8B732 /* SplitNavigationController.swift in Sources */,
 				D6B30E09254BAF63009CAEE5 /* ImageGrayscalifier.swift in Sources */,
 				D6A6C10F25B62D2400298D0F /* DiskCache.swift in Sources */,
 				D6B81F3C2560365300F6E31D /* RefreshableViewController.swift in Sources */,

Tusker/Screens/Main/MainSplitViewController.swift

@@ -20,8 +20,11 @@ class MainSplitViewController: UISplitViewController {
     
     private var tabBarViewController: MainTabBarViewController!
     
-    private var secondaryNavController: UINavigationController! {
+//    private var secondaryNavController: UINavigationController! {
-        viewController(for: .secondary) as? UINavigationController
+//        viewController(for: .secondary) as? UINavigationController
+//    }
+    private var secondaryNavController: SplitNavigationController! {
+        viewController(for: .secondary) as? SplitNavigationController
     }
     
     init(mastodonController: MastodonController) {
@@ -46,9 +49,10 @@ class MainSplitViewController: UISplitViewController {
         setViewController(sidebar, for: .primary)
         primaryBackgroundStyle = .sidebar
 
-        let secondaryNav = EnhancedNavigationViewController()
+//        let secondaryNav = EnhancedNavigationViewController()
-        secondaryNav.useBrowserStyleNavigation = true
+//        secondaryNav.useBrowserStyleNavigation = true
-        setViewController(secondaryNav, for: .secondary)
+        let splitNav = SplitNavigationController()
+        setViewController(splitNav, for: .secondary)
         // don't unnecesarily construct a content VC unless the we're in actually split mode
         // when we change from compact -> split for the first time, the VC will be transferred anyways
         if traitCollection.horizontalSizeClass != .compact {

Tusker/Screens/Main/MainTabBarViewController.swift

@@ -142,7 +142,7 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
             return vc
         } else {
             let nav = EnhancedNavigationViewController(rootViewController: vc)
-            nav.useBrowserStyleNavigation = true
+//            nav.useBrowserStyleNavigation = true
             return nav
         }
     }

Tusker/Screens/Utilities/SplitNavigationController.swift

@@ -0,0 +1,262 @@
+//
+//  SplitNavigationController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 7/1/22.
+//  Copyright © 2022 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+
+class SplitNavigationController: UIViewController {
+    
+    private let rootNav = SplitRootNavigationController()
+    private let secondaryNav = SplitSecondaryNavigationController()
+    private let separatorView = UIView()
+    
+    private var constraints: [NSLayoutConstraint] = []
+    
+    var viewControllers: [UIViewController] {
+        get {
+            return rootNav.viewControllers + secondaryNav.viewControllers
+        }
+        set {
+            if newValue.isEmpty {
+                rootNav.viewControllers = []
+                secondaryNav.viewControllers = []
+            } else if canShowSecondaryNav {
+                var newValue = newValue
+                rootNav.viewControllers = [newValue.removeFirst()]
+                secondaryNav.viewControllers = newValue
+            } else {
+                rootNav.viewControllers = newValue
+                secondaryNav.viewControllers = []
+            }
+            updateSecondaryNavVisibility()
+        }
+    }
+    
+    /// This property is only valid after the view has been laid out.
+    private var canShowSecondaryNav: Bool {
+        // minimum of 360pt for each column
+        // this allows split navigation on all ipads in portrait w/ sidebar hidden and in landscape (regardless of sidebar)
+        (viewIfLoaded?.bounds.width ?? 0) >= 720
+    }
+    
+    init(rootViewController: UIViewController? = nil) {
+        super.init(nibName: nil, bundle: nil)
+        
+        rootNav.showImpl = { [unowned self] vc, sender in
+            if self.canShowSecondaryNav {
+                self.setSecondaryViewControllers([vc], animated: true)
+                
+                // the split nav shouldn't really be reaching down into the inner VCs like this,
+                // but I can't think of a cleaner way
+                if let tableVC = sender as? UITableViewController,
+                   let selectedIndexPath = tableVC.tableView.indexPathForSelectedRow {
+                    tableVC.tableView.deselectRow(at: selectedIndexPath, animated: true)
+                }
+            } else {
+                self.rootNav.pushViewController(vc, animated: true)
+            }
+        }
+        secondaryNav.closeSecondaryImpl = { [unowned self] in
+            self.popToRootViewController(animated: true)
+        }
+        
+        if let rootViewController {
+            rootNav.viewControllers = [rootViewController]
+        }
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        
+        embedChild(rootNav, layout: false)
+        embedChild(secondaryNav, layout: false)
+        rootNav.view.translatesAutoresizingMaskIntoConstraints = false
+        secondaryNav.view.translatesAutoresizingMaskIntoConstraints = false
+
+        separatorView.backgroundColor = .separator
+        separatorView.translatesAutoresizingMaskIntoConstraints = false
+        view.addSubview(separatorView)
+        
+        NSLayoutConstraint.activate([
+            rootNav.view.topAnchor.constraint(equalTo: view.topAnchor),
+            rootNav.view.bottomAnchor.constraint(equalTo: view.bottomAnchor),
+            rootNav.view.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+
+            separatorView.topAnchor.constraint(equalTo: view.topAnchor),
+            separatorView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
+            separatorView.leadingAnchor.constraint(equalTo: rootNav.view.trailingAnchor),
+            separatorView.widthAnchor.constraint(equalToConstant: 0.5),
+
+            secondaryNav.view.topAnchor.constraint(equalTo: view.topAnchor),
+            secondaryNav.view.bottomAnchor.constraint(equalTo: view.bottomAnchor),
+            secondaryNav.view.leadingAnchor.constraint(equalTo: separatorView.trailingAnchor),
+        ])
+
+        updateSecondaryNavVisibility()
+    }
+    
+    override func show(_ vc: UIViewController, sender: Any?) {
+        if !canShowSecondaryNav {
+            rootNav.pushViewController(vc, animated: true)
+        } else if rootNav.viewControllers.isEmpty {
+            rootNav.pushViewController(vc, animated: false)
+        } else {
+            secondaryNav.pushViewController(vc, animated: true)
+        }
+        updateSecondaryNavVisibility()
+    }
+    
+    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
+        super.traitCollectionDidChange(previousTraitCollection)
+        
+        
+    }
+    
+    override func viewWillLayoutSubviews() {
+        super.viewWillLayoutSubviews()
+
+        if !isLayingOutForAnimation {
+            updateSecondaryNavVisibility()
+        }
+    }
+    
+    private func updateSecondaryNavVisibility() {
+        guard isViewLoaded else {
+            return
+        }
+        
+        if canShowSecondaryNav {
+            if rootNav.viewControllers.count > 1 {
+                var vcs = rootNav.viewControllers
+                let root = vcs.removeFirst()
+                rootNav.viewControllers = [root]
+                // this shouldn't be necessary since the vcs are removed from their parent vc by setting rootNav.viewControllers
+                // but it doesn't remove the views from their superview (until the next runloop iteration?)
+                // so we need to do that ourselves before we can set them on the secondary nav (otherwise it raises an exception)
+                vcs.forEach { $0.removeViewAndController() }
+                secondaryNav.viewControllers = vcs
+            }
+        } else {
+            if !secondaryNav.viewControllers.isEmpty {
+                let firstSecondary = secondaryNav.viewControllers.first!
+                // remove the left bar button item so that the builtin Back item shows
+                if firstSecondary.navigationItem.leftBarButtonItem?.tag == ViewTags.splitNavCloseSecondaryButton {
+                    firstSecondary.navigationItem.leftBarButtonItem = nil
+                }
+                rootNav.viewControllers.append(contentsOf: secondaryNav.viewControllers)
+                secondaryNav.viewControllers = []
+            }
+        }
+        
+        setSecondaryVisible(canShowSecondaryNav && !secondaryNav.viewControllers.isEmpty)
+    }
+    
+    private func setSecondaryVisible(_ visible: Bool) {
+        guard isViewLoaded else {
+            return
+        }
+        
+        NSLayoutConstraint.deactivate(constraints)
+        if visible {
+            constraints = [
+                rootNav.view.trailingAnchor.constraint(equalTo: view.centerXAnchor),
+                secondaryNav.view.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+            ]
+        } else {
+            constraints = [
+                rootNav.view.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+                secondaryNav.view.widthAnchor.constraint(equalTo: view.widthAnchor, multiplier: 0.5),
+            ]
+        }
+        NSLayoutConstraint.activate(constraints)
+    }
+    
+    private func setSecondaryViewControllers(_ vcs: [UIViewController], animated: Bool) {
+        if animated {
+            if vcs.isEmpty {
+                popToRootViewController(animated: true)
+            } else {
+                let wasVisible = !secondaryNav.viewControllers.isEmpty
+                secondaryNav.viewControllers = vcs
+                secondaryNav.view.frame = CGRect(x: view.bounds.width, y: 0, width: view.bounds.width / 2, height: view.bounds.height)
+                secondaryNav.view.layoutIfNeeded()
+                if !wasVisible {
+                    let animator = UIViewPropertyAnimator(duration: 0.35, curve: .easeInOut) {
+                        self.updateSecondaryNavVisibility()
+                        self.view.layoutIfNeeded()
+                    }
+                    animator.startAnimation()
+                }
+            }
+        } else {
+            secondaryNav.viewControllers = vcs
+            updateSecondaryNavVisibility()
+        }
+    }
+    
+    private var isLayingOutForAnimation = false
+    
+    func popToRootViewController(animated: Bool) {
+        if animated {
+            // we don't update secondaryNav.viewControllers until after the animation is completed
+            // otherwise the secondary nav's contents disappear immediately, rather than sliding off-screen
+            let animator = UIViewPropertyAnimator(duration: 0.35, curve: .easeInOut) {
+                self.isLayingOutForAnimation = true
+                self.setSecondaryVisible(false)
+                self.view.layoutIfNeeded()
+            }
+            animator.addCompletion { _ in
+                self.secondaryNav.viewControllers = []
+                self.isLayingOutForAnimation = false
+//                self.updateSecondaryNavVisibility()
+            }
+            animator.startAnimation()
+        } else {
+            self.secondaryNav.viewControllers = []
+            self.updateSecondaryNavVisibility()
+        }
+    }
+
+}
+
+private class SplitRootNavigationController: UINavigationController {
+    fileprivate var showImpl: ((UIViewController, Any?) -> Void)!
+    
+    override func show(_ vc: UIViewController, sender: Any?) {
+        showImpl(vc, sender)
+    }
+}
+
+private class SplitSecondaryNavigationController: EnhancedNavigationViewController {
+    fileprivate var closeSecondaryImpl: (() -> Void)!
+    
+    override var viewControllers: [UIViewController] {
+        didSet {
+            if let first = viewControllers.first {
+                configureSecondarySplitCloseButton(for: first)
+            }
+        }
+    }
+    
+    private func configureSecondarySplitCloseButton(for viewController: UIViewController) {
+        guard viewController.navigationItem.leftBarButtonItem?.tag != ViewTags.splitNavCloseSecondaryButton else {
+            return
+        }
+        let item = UIBarButtonItem(title: "Close", style: .done, target: self, action: #selector(closeSecondary))
+        item.tag = ViewTags.splitNavCloseSecondaryButton
+        viewController.navigationItem.leftBarButtonItem = item
+    }
+    
+    @objc private func closeSecondary() {
+        closeSecondaryImpl()
+    }
+    
+}

Tusker/Screens/Utilities/UIViewController+Children.swift

@@ -10,7 +10,7 @@ import UIKit
 
 // Based on MVCTodo by Dave DeLong: https://github.com/davedelong/MVCTodo/blob/841649dd6aa31bacda3ad7ef9a9a836f66281e50/MVCTodo/Extensions/UIViewController.swift
 extension UIViewController {
-    func embedChild(_ newChild: UIViewController, in container: UIView? = nil) {
+    func embedChild(_ newChild: UIViewController, in container: UIView? = nil, layout: Bool = true) {
         // if the view controller is already a child of something else, remove it
         if let oldParent = newChild.parent, oldParent != self {
             newChild.beginAppearanceTransition(false, animated: false)
@@ -36,7 +36,7 @@ extension UIViewController {
             newChild.beginAppearanceTransition(true, animated: false)
             addChild(newChild)
             newChild.didMove(toParent: self)
-            targetContainer.embedSubview(newChild.view)
+            targetContainer.embedSubview(newChild.view, layout: layout)
             newChild.endAppearanceTransition()
         } else {
             // the view controller is already a child
@@ -45,7 +45,7 @@ extension UIViewController {
             // we don't do the appearance transition stuff here,
             // because the vc is already a child, so *presumably*
             // that transition stuff has already appened
-            targetContainer.embedSubview(newChild.view)
+            targetContainer.embedSubview(newChild.view, layout: layout)
         }
     }
     
@@ -57,16 +57,18 @@ extension UIViewController {
 
 // Based on MVCTodo by Dave DeLong: https://github.com/davedelong/MVCTodo/blob/841649dd6aa31bacda3ad7ef9a9a836f66281e50/MVCTodo/Extensions/UIView.swift
 extension UIView {
-    func embedSubview(_ subview: UIView) {
+    func embedSubview(_ subview: UIView, layout: Bool = true) {
         if subview.superview == self { return }
         
         if subview.superview != nil {
             subview.removeFromSuperview()
         }
         
-        subview.frame = bounds
         addSubview(subview)
         
+        if layout {
+            subview.frame = bounds
+            
             NSLayoutConstraint.activate([
                 subview.leadingAnchor.constraint(equalTo: leadingAnchor),
                 subview.trailingAnchor.constraint(equalTo: trailingAnchor),
@@ -74,6 +76,7 @@ extension UIView {
                 subview.bottomAnchor.constraint(equalTo: bottomAnchor)
             ])
         }
+    }
     
     func isContainedWithin(_ other: UIView) -> Bool {
         var current: UIView? = self

Tusker/ViewTags.swift

@@ -16,4 +16,5 @@ struct ViewTags {
     static let navBackBarButton = 42003
     static let navForwardBarButton = 42004
     static let navEmptyTitleView = 42005
+    static let splitNavCloseSecondaryButton = 42006
 }