Promise: add background task extension

2 files changed, 61 insertions, 0 deletions

diff --git a/ios/MullvadVPN.xcodeproj/project.pbxproj b/ios/MullvadVPN.xcodeproj/project.pbxproj
index 6158d44473..52571baf85 100644
--- a/ios/MullvadVPN.xcodeproj/project.pbxproj
+++ b/ios/MullvadVPN.xcodeproj/project.pbxproj
@@ -27,6 +27,7 @@
 		581CBCEE229826FD00727D7F /* StaticTableViewDataSource.swift in Sources */ = {isa = PBXBuildFile; fileRef = 581CBCED229826FD00727D7F /* StaticTableViewDataSource.swift */; };
 		581FC4FA2695ACE100AA97BA /* Account.strings in Resources */ = {isa = PBXBuildFile; fileRef = 581FC4F82695ACE100AA97BA /* Account.strings */; };
 		5823FA5026CA690600283BF8 /* OSLogHandler.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5823FA4F26CA690600283BF8 /* OSLogHandler.swift */; };
+		5820674926E63EC900655B05 /* Promise+BackgroundTask.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5820674826E63EC800655B05 /* Promise+BackgroundTask.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 */; };
@@ -312,6 +313,7 @@
 		581503A524D6F4AE00C9C50E /* Logging.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Logging.swift; sourceTree = "<group>"; };
 		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>"; };
 		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>"; };
@@ -771,6 +773,7 @@
 				58E1337426D2BEC400CC316B /* Promise+Optional.swift */,
 				58E1337826D2BEDD00CC316B /* Promise+ReceiveOn.swift */,
 				58E1338026D2BF5C00CC316B /* Promise+Result.swift */,
+				5820674826E63EC800655B05 /* Promise+BackgroundTask.swift */,
 			);
 			path = Promise;
 			sourceTree = "<group>";
@@ -1160,6 +1163,7 @@
 				5873884D239E6D7E00E96C4E /* EmbeddedViewContainerView.swift in Sources */,
 				583BC70724FE4DC500C9DE04 /* Optional+DispatchQueue.swift in Sources */,
 				58F3C0A4249CB069003E76BE /* HeaderBarView.swift in Sources */,
+				5820674926E63EC900655B05 /* Promise+BackgroundTask.swift in Sources */,
 				58B9EB132488ED2100095626 /* AlertPresenter.swift in Sources */,
 				587A01FC23F1F0BE00B68763 /* SimulatorTunnelProviderHost.swift in Sources */,
 				5862805422428EF100F5A6E1 /* TranslucentButtonBlurView.swift in Sources */,
diff --git a/ios/MullvadVPN/Promise/Promise+BackgroundTask.swift b/ios/MullvadVPN/Promise/Promise+BackgroundTask.swift
new file mode 100644
index 0000000000..1d7bfc3280
--- /dev/null
+++ b/ios/MullvadVPN/Promise/Promise+BackgroundTask.swift
@@ -0,0 +1,57 @@
+//
+//  Promise+BackgroundTask.swift
+//  Promise+BackgroundTask
+//
+//  Created by pronebird on 06/09/2021.
+//  Copyright © 2021 Mullvad VPN AB. All rights reserved.
+//
+
+import UIKit
+
+extension Promise {
+
+    /// Start the background task for the duration of the upstream execution.
+    func requestBackgroundTime(taskName: String? = nil) -> Promise<Value> {
+        return Promise<Value> { resolver in
+            var backgroundTaskIdentifier: UIBackgroundTaskIdentifier?
+
+            let beginBackgroundTask = {
+                backgroundTaskIdentifier = UIApplication.shared.beginBackgroundTask(withName: taskName) {
+                    resolver.resolve(completion: .cancelled)
+                }
+            }
+
+            let endBackgroundTask = {
+                guard let taskIdentifier = backgroundTaskIdentifier,
+                      taskIdentifier != .invalid else { return }
+
+                UIApplication.shared.endBackgroundTask(taskIdentifier)
+                backgroundTaskIdentifier = nil
+            }
+
+            let endBackgroundTaskOnMainQueue = {
+                if Thread.isMainThread {
+                    endBackgroundTask()
+                } else {
+                    DispatchQueue.main.async(execute: endBackgroundTask)
+                }
+            }
+
+            if Thread.isMainThread {
+                beginBackgroundTask()
+            } else {
+                DispatchQueue.main.async(execute: beginBackgroundTask)
+            }
+
+            resolver.setCancelHandler {
+                endBackgroundTaskOnMainQueue()
+            }
+
+            self.observe { completion in
+                resolver.resolve(completion: completion)
+
+                endBackgroundTaskOnMainQueue()
+            }
+        }
+    }
+}