Add custom navigation controller

3 files changed, 107 insertions, 1 deletions

diff --git a/ios/MullvadVPN.xcodeproj/project.pbxproj b/ios/MullvadVPN.xcodeproj/project.pbxproj
index 4ccdcc0649..6f4e0914b3 100644
--- a/ios/MullvadVPN.xcodeproj/project.pbxproj
+++ b/ios/MullvadVPN.xcodeproj/project.pbxproj
@@ -53,6 +53,7 @@
 		581CBCEE229826FD00727D7F /* StaticTableViewDataSource.swift in Sources */ = {isa = PBXBuildFile; fileRef = 581CBCED229826FD00727D7F /* StaticTableViewDataSource.swift */; };
 		58293FB125124117005D0BB5 /* CustomTextField.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58293FB025124117005D0BB5 /* CustomTextField.swift */; };
 		58293FB3251241B4005D0BB5 /* CustomTextView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58293FB2251241B3005D0BB5 /* CustomTextView.swift */; };
+		58293FB725138B88005D0BB5 /* CustomNavigationController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58293FB625138B88005D0BB5 /* CustomNavigationController.swift */; };
 		582AE3102440A6CA00E6733A /* AccountTokenInput.swift in Sources */ = {isa = PBXBuildFile; fileRef = 582AE30F2440A6CA00E6733A /* AccountTokenInput.swift */; };
 		582AE3122440CA0D00E6733A /* AccountTokenInputTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 582AE3112440CA0D00E6733A /* AccountTokenInputTests.swift */; };
 		582AE3132440CA2700E6733A /* AccountTokenInput.swift in Sources */ = {isa = PBXBuildFile; fileRef = 582AE30F2440A6CA00E6733A /* AccountTokenInput.swift */; };
@@ -288,6 +289,7 @@
 		581CBCED229826FD00727D7F /* StaticTableViewDataSource.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StaticTableViewDataSource.swift; sourceTree = "<group>"; };
 		58293FB025124117005D0BB5 /* CustomTextField.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CustomTextField.swift; sourceTree = "<group>"; };
 		58293FB2251241B3005D0BB5 /* CustomTextView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CustomTextView.swift; sourceTree = "<group>"; };
+		58293FB625138B88005D0BB5 /* CustomNavigationController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CustomNavigationController.swift; sourceTree = "<group>"; };
 		582AE30F2440A6CA00E6733A /* AccountTokenInput.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AccountTokenInput.swift; sourceTree = "<group>"; };
 		582AE3112440CA0D00E6733A /* AccountTokenInputTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AccountTokenInputTests.swift; sourceTree = "<group>"; };
 		582BB1AE229566420055B6EF /* SettingsCell.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SettingsCell.swift; sourceTree = "<group>"; };
@@ -551,6 +553,7 @@
 				58AB9DEB2501040C006C5526 /* ConsentViewController.xib */,
 				5896AE83246D5889005B36CB /* CustomDateComponentsFormatting.swift */,
 				582BB1B0229569620055B6EF /* CustomNavigationBar.swift */,
+				58293FB625138B88005D0BB5 /* CustomNavigationController.swift */,
 				58293FB025124117005D0BB5 /* CustomTextField.swift */,
 				58293FB2251241B3005D0BB5 /* CustomTextView.swift */,
 				58C6B35D22BBBFE3003C19AD /* Data+HexCoding.swift */,
@@ -1049,6 +1052,7 @@
 				58CCA01E2242787B004F3011 /* AccountTextField.swift in Sources */,
 				587AD7CA2342283900E93A53 /* Account.swift in Sources */,
 				58F840AF2464382C0044E708 /* KeychainItemRevision.swift in Sources */,
+				58293FB725138B88005D0BB5 /* CustomNavigationController.swift in Sources */,
 				587425C12299833500CA2045 /* RootContainerViewController.swift in Sources */,
 				580EE20124B321D500F9D8A1 /* OperationProtocol.swift in Sources */,
 				5896AE84246D5889005B36CB /* CustomDateComponentsFormatting.swift in Sources */,
diff --git a/ios/MullvadVPN/CustomNavigationController.swift b/ios/MullvadVPN/CustomNavigationController.swift
new file mode 100644
index 0000000000..1a7e7bb49d
--- /dev/null
+++ b/ios/MullvadVPN/CustomNavigationController.swift
@@ -0,0 +1,102 @@
+//
+//  CustomNavigationController.swift
+//  MullvadVPN
+//
+//  Created by pronebird on 17/09/2020.
+//  Copyright © 2020 Mullvad VPN AB. All rights reserved.
+//
+
+import Foundation
+import UIKit
+
+enum NavigationPopTrigger {
+    case backButton
+    case interactiveGesture
+}
+
+protocol ConditionalNavigation: class {
+    func shouldPopNavigationItem(_ navigationItem: UINavigationItem, trigger: NavigationPopTrigger) -> Bool
+}
+
+class CustomNavigationController: UINavigationController, UINavigationBarDelegate {
+
+    private static let classInit: Void = {
+        swizzleMethod(
+            aClass: CustomNavigationController.self,
+            originalSelector: #selector(UINavigationBarDelegate.navigationBar(_:shouldPop:)),
+            newSelector: #selector(customNavigationController_navigationBar(_:shouldPop:))
+        )
+    }()
+
+    private var popGestureRecognizerDelegate: CustomPopGestureRecognizerDelegate?
+
+    override func viewDidLoad() {
+        super.viewDidLoad()
+
+        _ = Self.classInit
+
+        popGestureRecognizerDelegate = CustomPopGestureRecognizerDelegate(navigationController: self, systemGestureRecognizerDelegate: interactivePopGestureRecognizer?.delegate)
+
+        // Replace the system interactive gesture recognizer
+        interactivePopGestureRecognizer?.delegate = popGestureRecognizerDelegate
+    }
+
+    @objc dynamic func customNavigationController_navigationBar(_ navigationBar: UINavigationBar, shouldPop item: UINavigationItem) -> Bool {
+        var shouldPop = true
+
+        if let conformingViewController = topViewController as? ConditionalNavigation {
+            shouldPop = conformingViewController.shouldPopNavigationItem(item, trigger: .backButton)
+        }
+
+        // Only call super implementation when we want to pop the controller
+        if shouldPop {
+            // Call super implementation
+            return customNavigationController_navigationBar(navigationBar, shouldPop: item)
+        } else {
+            return shouldPop
+        }
+    }
+}
+
+private class CustomPopGestureRecognizerDelegate: NSObject, UIGestureRecognizerDelegate {
+
+    private let systemGestureRecognizerDelegate: UIGestureRecognizerDelegate?
+    private weak var navigationController: UINavigationController?
+
+    init(navigationController: UINavigationController, systemGestureRecognizerDelegate: UIGestureRecognizerDelegate?) {
+        self.navigationController = navigationController
+        self.systemGestureRecognizerDelegate = systemGestureRecognizerDelegate
+    }
+
+    override func responds(to aSelector: Selector!) -> Bool {
+        if Self.instancesRespond(to: aSelector) {
+            return true
+        } else {
+            return systemGestureRecognizerDelegate?.responds(to: aSelector) ?? false
+        }
+    }
+
+    override func forwardingTarget(for aSelector: Selector!) -> Any? {
+        let shouldForward = systemGestureRecognizerDelegate?.responds(to: aSelector) ?? false
+
+        if shouldForward {
+            return systemGestureRecognizerDelegate
+        } else {
+            return nil
+        }
+    }
+
+    // MARK: - UIGestureRecognizerDelegate
+
+    func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
+        let shouldBegin = systemGestureRecognizerDelegate?.gestureRecognizerShouldBegin?(gestureRecognizer) ?? true
+
+        guard let navigationController = navigationController,
+            let topItem = navigationController.navigationBar.topItem,
+            let conformingViewController = navigationController.topViewController as? ConditionalNavigation else {
+                return shouldBegin
+        }
+
+        return shouldBegin && conformingViewController.shouldPopNavigationItem(topItem, trigger: .interactiveGesture)
+    }
+}
diff --git a/ios/MullvadVPN/SettingsNavigationController.swift b/ios/MullvadVPN/SettingsNavigationController.swift
index 87527b77cb..b582b78bca 100644
--- a/ios/MullvadVPN/SettingsNavigationController.swift
+++ b/ios/MullvadVPN/SettingsNavigationController.swift
@@ -9,7 +9,7 @@
 import Foundation
 import UIKit
 
-class SettingsNavigationController: UINavigationController {
+class SettingsNavigationController: CustomNavigationController {
 
     override func viewDidLoad() {
         super.viewDidLoad()