Merge branch 'refactor-alert-presenter'

3 files changed, 95 insertions, 41 deletions

diff --git a/ios/MullvadVPN.xcodeproj/project.pbxproj b/ios/MullvadVPN.xcodeproj/project.pbxproj
index 12f9d22b1e..b478a6570d 100644
--- a/ios/MullvadVPN.xcodeproj/project.pbxproj
+++ b/ios/MullvadVPN.xcodeproj/project.pbxproj
@@ -28,6 +28,7 @@
 		581FC4FA2695ACE100AA97BA /* Account.strings in Resources */ = {isa = PBXBuildFile; fileRef = 581FC4F82695ACE100AA97BA /* Account.strings */; };
 		5820674926E63EC900655B05 /* Promise+BackgroundTask.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5820674826E63EC800655B05 /* Promise+BackgroundTask.swift */; };
 		5823FA5026CA690600283BF8 /* OSLogHandler.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5823FA4F26CA690600283BF8 /* OSLogHandler.swift */; };
+		5820675E26E6839900655B05 /* PresentAlertOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5820675D26E6839900655B05 /* PresentAlertOperation.swift */; };
 		58293FAE2510CA58005D0BB5 /* ProblemReportViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58293FAC2510CA58005D0BB5 /* ProblemReportViewController.swift */; };
 		58293FB125124117005D0BB5 /* CustomTextField.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58293FB025124117005D0BB5 /* CustomTextField.swift */; };
 		58293FB3251241B4005D0BB5 /* CustomTextView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 58293FB2251241B3005D0BB5 /* CustomTextView.swift */; };
@@ -319,6 +320,7 @@
 		581CBCED229826FD00727D7F /* StaticTableViewDataSource.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StaticTableViewDataSource.swift; sourceTree = "<group>"; };
 		581FC4F92695ACE100AA97BA /* en */ = {isa = PBXFileReference; lastKnownFileType = text.plist.strings; name = en; path = en.lproj/Account.strings; sourceTree = "<group>"; };
 		5820674826E63EC800655B05 /* Promise+BackgroundTask.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Promise+BackgroundTask.swift"; sourceTree = "<group>"; };
+		5820675D26E6839900655B05 /* PresentAlertOperation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PresentAlertOperation.swift; sourceTree = "<group>"; };
 		5823FA4F26CA690600283BF8 /* OSLogHandler.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OSLogHandler.swift; sourceTree = "<group>"; };
 		58293FAC2510CA58005D0BB5 /* ProblemReportViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ProblemReportViewController.swift; sourceTree = "<group>"; };
 		58293FB025124117005D0BB5 /* CustomTextField.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CustomTextField.swift; sourceTree = "<group>"; };
@@ -533,6 +535,7 @@
 				58E973DD24850EB600096F90 /* AsyncOperation.swift */,
 				580EE20524B3222200F9D8A1 /* ExclusivityController.swift */,
 				5846226926E0E6FA0035F7C2 /* ReceiptRefreshOperation.swift */,
+				5820675D26E6839900655B05 /* PresentAlertOperation.swift */,
 			);
 			path = Operations;
 			sourceTree = "<group>";
@@ -1193,6 +1196,7 @@
 				5835B7CC233B76CB0096D79F /* TunnelManager.swift in Sources */,
 				58FEEB46260A028D00A621A8 /* GeoJSON.swift in Sources */,
 				5815039724D6ECAE00C9C50E /* CustomFormatLogHandler.swift in Sources */,
+				5820675E26E6839900655B05 /* PresentAlertOperation.swift in Sources */,
 				5815039D24D6ECE600C9C50E /* TextFileOutputStream.swift in Sources */,
 				581CBCEE229826FD00727D7F /* StaticTableViewDataSource.swift in Sources */,
 				58CE5E64224146200008646E /* AppDelegate.swift in Sources */,
diff --git a/ios/MullvadVPN/AlertPresenter.swift b/ios/MullvadVPN/AlertPresenter.swift
index 8594c8211e..954a641e28 100644
--- a/ios/MullvadVPN/AlertPresenter.swift
+++ b/ios/MullvadVPN/AlertPresenter.swift
@@ -9,20 +9,20 @@
 import Foundation
 import UIKit
 
-private let kUIAlertControllerDidDissmissNotification = Notification.Name("UIAlertControllerDidDismiss")
-
 class AlertPresenter {
-    private enum ExclusivityCategory {
-        case exclusive
-    }
+    static let alertControllerDidDismissNotification = Notification.Name("UIAlertControllerDidDismiss")
 
-    private let operationQueue = OperationQueue()
-    private lazy var exclusivityController = ExclusivityController<ExclusivityCategory>(operationQueue: operationQueue)
+    private let operationQueue: OperationQueue = {
+        let operationQueue = OperationQueue()
+        operationQueue.name = "AlertPresenterQueue"
+        operationQueue.maxConcurrentOperationCount = 1
+        return operationQueue
+    }()
 
     private static let initClass: Void = {
         /// Swizzle `viewDidDisappear` on `UIAlertController` in order to be able to
         /// detect when the controller disappears.
-        /// The event is broadcasted via `kUIAlertControllerDidDissmissNotification` notification.
+        /// The event is broadcasted via `AlertPresenter.alertControllerDidDismissNotification` notification.
         swizzleMethod(aClass: UIAlertController.self, originalSelector: #selector(UIAlertController.viewDidDisappear(_:)), newSelector: #selector(UIAlertController.alertPresenter_viewDidDisappear(_:)))
     }()
 
@@ -37,11 +37,14 @@ class AlertPresenter {
             presentCompletion: presentCompletion
         )
 
-        exclusivityController.addOperation(operation, categories: [.exclusive])
+        operationQueue.addOperation(operation)
     }
 
-}
+    func cancelAll() {
+        operationQueue.cancelAllOperations()
+    }
 
+}
 
 fileprivate extension UIAlertController {
     @objc dynamic func alertPresenter_viewDidDisappear(_ animated: Bool) {
@@ -49,37 +52,7 @@ fileprivate extension UIAlertController {
         alertPresenter_viewDidDisappear(animated)
 
         if presentingViewController == nil {
-            NotificationCenter.default.post(name: kUIAlertControllerDidDissmissNotification, object: self)
-        }
-    }
-}
-
-
-private class PresentAlertOperation: AsyncOperation {
-    private let alertController: UIAlertController
-    private let presentingController: UIViewController
-    private var dismissalObserver: NSObjectProtocol?
-    private let presentCompletion: (() -> Void)?
-
-    init(alertController: UIAlertController, presentingController: UIViewController, presentCompletion: (() -> Void)? = nil) {
-        self.alertController = alertController
-        self.presentingController = presentingController
-        self.presentCompletion = presentCompletion
-
-        super.init()
-    }
-
-    override func main() {
-        DispatchQueue.main.async {
-            self.dismissalObserver = NotificationCenter.default.addObserver(
-                forName: kUIAlertControllerDidDissmissNotification,
-                object: self.alertController,
-                queue: nil,
-                using: { [weak self] (note) in
-                    self?.finish()
-            })
-
-            self.presentingController.present(self.alertController, animated: true, completion: self.presentCompletion)
+            NotificationCenter.default.post(name: AlertPresenter.alertControllerDidDismissNotification, object: self)
         }
     }
 }
diff --git a/ios/MullvadVPN/Operations/PresentAlertOperation.swift b/ios/MullvadVPN/Operations/PresentAlertOperation.swift
new file mode 100644
index 0000000000..0bc420f770
--- /dev/null
+++ b/ios/MullvadVPN/Operations/PresentAlertOperation.swift
@@ -0,0 +1,77 @@
+//
+//  PresentAlertOperation.swift
+//  PresentAlertOperation
+//
+//  Created by pronebird on 06/09/2021.
+//  Copyright © 2021 Mullvad VPN AB. All rights reserved.
+//
+
+import UIKit
+
+class PresentAlertOperation: AsyncOperation {
+    private let alertController: UIAlertController
+    private let presentingController: UIViewController
+    private let presentCompletion: (() -> Void)?
+
+    init(alertController: UIAlertController, presentingController: UIViewController, presentCompletion: (() -> Void)? = nil) {
+        self.alertController = alertController
+        self.presentingController = presentingController
+        self.presentCompletion = presentCompletion
+
+        super.init()
+    }
+
+    override func cancel() {
+        DispatchQueue.main.async {
+            // Guard against executing cancellation more than once.
+            guard !self.isCancelled else { return }
+
+            // Guard against trying to dismiss the alert when operation hasn't started yet.
+            guard self.isExecuting else { return }
+
+            // Guard against dismissing controller during transition.
+            if !self.alertController.isBeingPresented && !self.alertController.isBeingDismissed {
+                self.dismissAndFinish()
+            }
+
+            // Call super implementation to toggle isCancelled flag
+            super.cancel()
+        }
+    }
+
+    override func main() {
+        DispatchQueue.main.async {
+            NotificationCenter.default.addObserver(
+                self,
+                selector: #selector(self.alertControllerDidDismiss(_:)),
+                name: AlertPresenter.alertControllerDidDismissNotification,
+                object: self.alertController
+            )
+
+            self.presentingController.present(self.alertController, animated: true) {
+                self.presentCompletion?()
+
+                // Alert operation was cancelled during transition?
+                if self.isCancelled {
+                    self.dismissAndFinish()
+                }
+            }
+        }
+    }
+
+    private func dismissAndFinish() {
+        NotificationCenter.default.removeObserver(
+            self,
+            name: AlertPresenter.alertControllerDidDismissNotification,
+            object: self.alertController
+        )
+
+        alertController.dismiss(animated: false) {
+            self.finish()
+        }
+    }
+
+    @objc private func alertControllerDidDismiss(_ note: Notification) {
+        finish()
+    }
+}