Merge pull request hotwired#50 from hotwired/tab-bar-switching

Ignore view and session lifecycle events when switching between tabs

Source/HotwireConfig.swift

@@ -36,9 +36,9 @@ public struct HotwireConfig {
     }
 
     /// The navigation controller used in `Navigator` for the main and modal stacks.
-    /// Must be a `UINavigationController` or subclass.
+    /// Must be a `HotwireNavigationController` or subclass.
     public var defaultNavigationController: () -> UINavigationController = {
-        UINavigationController()
+        HotwireNavigationController()
     }
 
     /// Optionally customize the web views used by each Turbo Session.

Source/HotwireNavigationController.swift

@@ -0,0 +1,70 @@
+import UIKit
+
+/// The `HotwireNavigationController` is a custom subclass of `UINavigationController` designed to enhance the management of `VisitableViewController` instances within a navigation stack.
+/// It tracks the reasons why a view controller appears or disappears, which is crucial for handling navigation in Hotwire-powered applications.
+/// - Important: If you are using a custom or third-party navigation controller, subclass `HotwireNavigationController` to integrate its behavior.
+///
+/// ## Usage Notes
+///
+/// - **Integrating with Custom Navigation Controllers:**
+///   If you're using a custom or third-party navigation controller, subclass `HotwireNavigationController` to incorporate the necessary behavior.
+///
+///   ```swift
+///   open class YourCustomNavigationController: HotwireNavigationController {
+///       // Make sure to always call super when overriding functions from `HotwireNavigationController`.
+///   }
+///   ```
+///
+/// - **Extensibility:**
+///   The class is marked as `open`, allowing you to subclass and extend its functionality to suit your specific needs.
+///
+/// ## Limitations
+///
+/// - **Other Container Controllers:**
+///   The current implementation focuses on `UINavigationController` and includes handling for `UITabBarController`. It does not provide out-of-the-box support for other container controllers like `UISplitViewController`.
+///
+/// - **Custom Navigation Setups:**
+///   For completely custom navigation setups or container controllers, you will need to implement similar logic to manage the `appearReason` and `disappearReason` of `VisitableViewController` instances.
+open class HotwireNavigationController: UINavigationController {
+    open override func pushViewController(_ viewController: UIViewController, animated: Bool) {
+        if let visitableViewController = viewController as? VisitableViewController {
+            visitableViewController.appearReason = .pushedOntoNavigationStack
+        }
+
+        if let topVisitableViewController = topViewController as? VisitableViewController {
+            topVisitableViewController.disappearReason = .coveredByPush
+        }
+
+        super.pushViewController(viewController, animated: animated)
+    }
+
+    open override func popViewController(animated: Bool) -> UIViewController? {
+        let poppedViewController = super.popViewController(animated: animated)
+        if let poppedVisitableViewController = poppedViewController as? VisitableViewController {
+            poppedVisitableViewController.disappearReason = .poppedFromNavigationStack
+        }
+
+        if let topVisitableViewController = topViewController as? VisitableViewController {
+            topVisitableViewController.appearReason = .revealedByPop
+        }
+
+        return poppedViewController
+    }
+
+    open override func viewWillAppear(_ animated: Bool) {
+        if let topVisitableViewController = topViewController as? VisitableViewController,
+           topVisitableViewController.disappearReason == .tabDeselected {
+            topVisitableViewController.appearReason = .tabSelected
+        }
+        super.viewWillAppear(animated)
+    }
+
+    open override func viewWillDisappear(_ animated: Bool) {
+        if tabBarController != nil,
+           let topVisitableViewController = topViewController as? VisitableViewController {
+            topVisitableViewController.disappearReason = .tabDeselected
+        }
+
+        super.viewWillDisappear(animated)
+    }
+}

Source/Turbo/Session/Session.swift

@@ -234,7 +234,7 @@ extension Session: VisitableDelegate {
             previousVisit = nil
         }
 
-        guard let topmostVisit = topmostVisit, let currentVisit = currentVisit else { return }
+        guard let topmostVisit, let currentVisit else { return }
 
         if isSnapshotCacheStale {
             clearSnapshotCache()
@@ -244,21 +244,33 @@ extension Session: VisitableDelegate {
         if isShowingStaleContent {
             reload()
             isShowingStaleContent = false
-        } else if visitable === topmostVisit.visitable && visitable.visitableViewController.isMovingToParent {
-            // Back swipe gesture canceled
+            return
+        }
+
+        // Back swipe gesture canceled.
+        if visitable === topmostVisit.visitable && visitable.visitableViewController.isMovingToParent {
             if topmostVisit.state == .completed {
                 currentVisit.cancel()
             } else {
                 visit(visitable, action: .advance)
             }
-        } else if visitable === currentVisit.visitable && currentVisit.state == .started {
-            // Navigating forward - complete navigation early
+            return
+        }
+
+        // Navigating forward - complete navigation early.
+        if visitable === currentVisit.visitable && currentVisit.state == .started {
             completeNavigationForCurrentVisit()
-        } else if visitable !== topmostVisit.visitable {
-            // Navigating backward from a web view screen to a web view screen.
+            return
+        }
+
+        // Navigating backward from a web view screen to a web view screen.
+        if visitable !== topmostVisit.visitable {
             visit(visitable, action: .restore)
-        } else if visitable === previousVisit?.visitable {
-            // Navigating backward from a native to a web view screen.
+            return
+        }
+
+        // Navigating backward from a native to a web view screen.
+        if visitable === previousVisit?.visitable {
             visit(visitable, action: .restore)
         }
     }

Source/Turbo/Visitable/VisitableViewController.swift

@@ -4,6 +4,8 @@ import WebKit
 open class VisitableViewController: UIViewController, Visitable {
     open weak var visitableDelegate: VisitableDelegate?
     open var visitableURL: URL!
+    var appearReason: AppearReason = .pushedOntoNavigationStack
+    var disappearReason: DisappearReason = .poppedFromNavigationStack
 
     public convenience init(url: URL) {
         self.init()
@@ -20,21 +22,25 @@ open class VisitableViewController: UIViewController, Visitable {
 
     override open func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(animated)
+        if appearReason == .tabSelected { return }
         visitableDelegate?.visitableViewWillAppear(self)
     }
 
     override open func viewDidAppear(_ animated: Bool) {
         super.viewDidAppear(animated)
+        if appearReason == .tabSelected { return }
         visitableDelegate?.visitableViewDidAppear(self)
     }
 
     override open func viewWillDisappear(_ animated: Bool) {
         super.viewWillDisappear(animated)
+        if disappearReason == .tabDeselected { return }
         visitableDelegate?.visitableViewWillDisappear(self)
     }
 
     override open func viewDidDisappear(_ animated: Bool) {
         super.viewDidDisappear(animated)
+        if disappearReason == .tabDeselected { return }
         visitableDelegate?.visitableViewDidDisappear(self)
     }
 
@@ -78,3 +84,17 @@ open class VisitableViewController: UIViewController, Visitable {
         ])
     }
 }
+
+extension VisitableViewController {
+    public enum AppearReason {
+        case pushedOntoNavigationStack
+        case revealedByPop
+        case tabSelected
+    }
+
+    public enum DisappearReason {
+        case coveredByPush
+        case poppedFromNavigationStack
+        case tabDeselected
+    }
+}