feat: add navigation pan pop gesture. resolve #407 #419

Mastodon/Scene/Share/NavigationController/AdaptiveStatusBarStyleNavigationController.swift

@@ -10,7 +10,41 @@ import UIKit
 // Make status bar style adaptive for child view controller
 // SeeAlso: `modalPresentationCapturesStatusBarAppearance`
 class AdaptiveStatusBarStyleNavigationController: UINavigationController {
+
+    private lazy var fullWidthBackGestureRecognizer = UIPanGestureRecognizer()
+
     override var childForStatusBarStyle: UIViewController? {
         visibleViewController
     }
 }
+
+// ref: https://stackoverflow.com/a/60598558/3797903
+extension AdaptiveStatusBarStyleNavigationController {
+    
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        setupFullWidthBackGesture()
+    }
+
+    private func setupFullWidthBackGesture() {
+        // The trick here is to wire up our full-width `fullWidthBackGestureRecognizer` to execute the same handler as
+        // the system `interactivePopGestureRecognizer`. That's done by assigning the same "targets" (effectively
+        // object and selector) of the system one to our gesture recognizer.
+        guard let interactivePopGestureRecognizer = interactivePopGestureRecognizer,
+              let targets = interactivePopGestureRecognizer.value(forKey: "targets")
+        else { return }
+
+        fullWidthBackGestureRecognizer.setValue(targets, forKey: "targets")
+        fullWidthBackGestureRecognizer.delegate = self
+        view.addGestureRecognizer(fullWidthBackGestureRecognizer)
+    }
+}
+
+// MARK: - UIGestureRecognizerDelegate
+extension AdaptiveStatusBarStyleNavigationController: UIGestureRecognizerDelegate {
+    func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
+        let isSystemSwipeToBackEnabled = interactivePopGestureRecognizer?.isEnabled == true
+        let isThereStackedViewControllers = viewControllers.count > 1
+        return isSystemSwipeToBackEnabled && isThereStackedViewControllers
+    }
+}