Use reference counting to disable proximity monitoring after audio message

Multiple overlapping activities require proximity monitoring (namely,
CallViewController and listening to audio messages).

These activities can overlap arbitrarily, so we use a reference counting
strategy to keep proximity monitoring on as long as one of these activities is
active.

Signal.xcodeproj/project.pbxproj

@@ -441,6 +441,7 @@
 		4CA5F793211E1F06008C2708 /* Toast.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4CA5F792211E1F06008C2708 /* Toast.swift */; };
 		4CB5F26720F6E1E2004D1B42 /* MenuActionsViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4CFF4C0920F55BBA005DA313 /* MenuActionsViewController.swift */; };
 		4CB5F26920F7D060004D1B42 /* MessageActions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4CB5F26820F7D060004D1B42 /* MessageActions.swift */; };
+		4CB93DC22180FF07004B9764 /* ProximityMonitoringManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4CB93DC12180FF07004B9764 /* ProximityMonitoringManager.swift */; };
 		4CC0B59C20EC5F2E00CF6EE0 /* ConversationConfigurationSyncOperation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4CC0B59B20EC5F2E00CF6EE0 /* ConversationConfigurationSyncOperation.swift */; };
 		4CC1ECF9211A47CE00CC13BE /* StoreKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 4CC1ECF8211A47CD00CC13BE /* StoreKit.framework */; settings = {ATTRIBUTES = (Weak, ); }; };
 		4CC1ECFB211A553000CC13BE /* AppUpdateNag.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4CC1ECFA211A553000CC13BE /* AppUpdateNag.swift */; };
@@ -1126,6 +1127,7 @@
 		4C9CA25C217E676900607C63 /* ZXingObjC.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = ZXingObjC.framework; path = ThirdParty/Carthage/Build/iOS/ZXingObjC.framework; sourceTree = "<group>"; };
 		4CA5F792211E1F06008C2708 /* Toast.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Toast.swift; sourceTree = "<group>"; };
 		4CB5F26820F7D060004D1B42 /* MessageActions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MessageActions.swift; sourceTree = "<group>"; };
+		4CB93DC12180FF07004B9764 /* ProximityMonitoringManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ProximityMonitoringManager.swift; sourceTree = "<group>"; };
 		4CC0B59B20EC5F2E00CF6EE0 /* ConversationConfigurationSyncOperation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ConversationConfigurationSyncOperation.swift; sourceTree = "<group>"; };
 		4CC1ECF8211A47CD00CC13BE /* StoreKit.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = StoreKit.framework; path = System/Library/Frameworks/StoreKit.framework; sourceTree = SDKROOT; };
 		4CC1ECFA211A553000CC13BE /* AppUpdateNag.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppUpdateNag.swift; sourceTree = "<group>"; };
@@ -1517,6 +1519,7 @@
 				45F170D51E315310003FC1F2 /* Weak.swift */,
 				4C858A51212DC5E1001B45D3 /* UIImage+OWS.swift */,
 				4C948FF62146EB4800349F0D /* BlockListCache.swift */,
+				4CB93DC12180FF07004B9764 /* ProximityMonitoringManager.swift */,
 			);
 			path = utils;
 			sourceTree = "<group>";
@@ -3152,6 +3155,7 @@
 			files = (
 				45F59A0A2029140500E8D2B0 /* OWSVideoPlayer.swift in Sources */,
 				45194F951FD7216600333B2C /* TSUnreadIndicatorInteraction.m in Sources */,
+				4CB93DC22180FF07004B9764 /* ProximityMonitoringManager.swift in Sources */,
 				34AC09E1211B39B100997B47 /* SelectThreadViewController.m in Sources */,
 				34AC09EF211B39B100997B47 /* ViewControllerUtils.m in Sources */,
 				346941A2215D2EE400B5BFAD /* OWSConversationColor.m in Sources */,

Signal/src/ViewControllers/CallViewController.swift

@@ -13,10 +13,15 @@ import SignalMessaging
 class CallViewController: OWSViewController, CallObserver, CallServiceObserver, CallAudioServiceDelegate {
 
     // Dependencies
+
     var callUIAdapter: CallUIAdapter {
         return AppEnvironment.shared.callService.callUIAdapter
     }
 
+    var proximityMonitoringManager: OWSProximityMonitoringManager {
+        return Environment.shared.proximityMonitoringManager
+    }
+
     // Feature Flag
     @objc public static let kShowCallViewOnSeparateWindow = true
 
@@ -165,6 +170,7 @@ class CallViewController: OWSViewController, CallObserver, CallServiceObserver,
     override func viewDidDisappear(_ animated: Bool) {
         super.viewDidDisappear(animated)
 
+        self.proximityMonitoringManager.remove(lifetime: self)
         UIDevice.current.isProximityMonitoringEnabled = false
 
         callDurationTimer?.invalidate()
@@ -173,7 +179,8 @@ class CallViewController: OWSViewController, CallObserver, CallServiceObserver,
 
     override func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(animated)
-        UIDevice.current.isProximityMonitoringEnabled = true
+        self.proximityMonitoringManager.add(lifetime: self)
+
         updateCallUI(callState: call.state)
 
         self.becomeFirstResponder()

SignalMessaging/environment/AppSetup.m

@@ -86,12 +86,14 @@ NS_ASSUME_NONNULL_BEGIN
 
         OWSAudioSession *audioSession = [OWSAudioSession new];
         OWSSounds *sounds = [[OWSSounds alloc] initWithPrimaryStorage:primaryStorage];
+        id<OWSProximityMonitoringManager> proximityMonitoringManager = [OWSProximityMonitoringManagerImpl new];
         LockInteractionController *lockInteractionController = [[LockInteractionController alloc] initDefault];
         OWSWindowManager *windowManager = [[OWSWindowManager alloc] initDefault];
         [Environment setShared:[[Environment alloc] initWithAudioSession:audioSession
+                                               lockInteractionController:lockInteractionController
                                                              preferences:preferences
+                                              proximityMonitoringManager:proximityMonitoringManager
                                                                   sounds:sounds
-                                               lockInteractionController:lockInteractionController
                                                            windowManager:windowManager]];
 
         [SSKEnvironment setShared:[[SSKEnvironment alloc] initWithContactsManager:contactsManager

SignalMessaging/environment/Environment.h

@@ -11,6 +11,8 @@
 @class OWSSounds;
 @class OWSWindowManager;
 
+@protocol OWSProximityMonitoringManager;
+
 /**
  *
  * Environment is a data and data accessor class.
@@ -24,16 +26,18 @@
 - (instancetype)init NS_UNAVAILABLE;
 
 - (instancetype)initWithAudioSession:(OWSAudioSession *)audioSession
+           lockInteractionController:(LockInteractionController *)lockInteractionController
                          preferences:(OWSPreferences *)preferences
+          proximityMonitoringManager:(id<OWSProximityMonitoringManager>)proximityMonitoringManager
                               sounds:(OWSSounds *)sounds
-           lockInteractionController:(LockInteractionController *)lockInteractionController
                        windowManager:(OWSWindowManager *)windowManager;
 
 @property (nonatomic, readonly) OWSAudioSession *audioSession;
 @property (nonatomic, readonly) OWSContactsManager *contactsManager;
+@property (nonatomic, readonly) LockInteractionController *lockInteractionController;
+@property (nonatomic, readonly) id<OWSProximityMonitoringManager> proximityMonitoringManager;
 @property (nonatomic, readonly) OWSPreferences *preferences;
 @property (nonatomic, readonly) OWSSounds *sounds;
-@property (nonatomic, readonly) LockInteractionController *lockInteractionController;
 @property (nonatomic, readonly) OWSWindowManager *windowManager;
 
 @property (class, nonatomic) Environment *shared;

SignalMessaging/environment/Environment.m

@@ -13,9 +13,10 @@ static Environment *sharedEnvironment = nil;
 
 @property (nonatomic) OWSAudioSession *audioSession;
 @property (nonatomic) OWSContactsManager *contactsManager;
+@property (nonatomic) LockInteractionController *lockInteractionController;
 @property (nonatomic) OWSPreferences *preferences;
+@property (nonatomic) id<OWSProximityMonitoringManager> proximityMonitoringManager;
 @property (nonatomic) OWSSounds *sounds;
-@property (nonatomic) LockInteractionController *lockInteractionController;
 @property (nonatomic) OWSWindowManager *windowManager;
 
 @end
@@ -49,9 +50,10 @@ static Environment *sharedEnvironment = nil;
 }
 
 - (instancetype)initWithAudioSession:(OWSAudioSession *)audioSession
+           lockInteractionController:(LockInteractionController *)lockInteractionController
                          preferences:(OWSPreferences *)preferences
+          proximityMonitoringManager:(id<OWSProximityMonitoringManager>)proximityMonitoringManager
                               sounds:(OWSSounds *)sounds
-           lockInteractionController:(LockInteractionController *)lockInteractionController
                        windowManager:(OWSWindowManager *)windowManager
 {
     self = [super init];
@@ -60,15 +62,17 @@ static Environment *sharedEnvironment = nil;
     }
 
     OWSAssertDebug(audioSession);
+    OWSAssertDebug(lockInteractionController);
     OWSAssertDebug(preferences);
+    OWSAssertDebug(proximityMonitoringManager);
     OWSAssertDebug(sounds);
-    OWSAssertDebug(lockInteractionController);
     OWSAssertDebug(windowManager);
 
     _audioSession = audioSession;
+    _lockInteractionController = lockInteractionController;
     _preferences = preferences;
+    _proximityMonitoringManager = proximityMonitoringManager;
     _sounds = sounds;
-    _lockInteractionController = lockInteractionController;
     _windowManager = windowManager;
 
     OWSSingletonAssert();

SignalMessaging/environment/OWSAudioSession.swift

@@ -44,6 +44,10 @@ public class OWSAudioSession: NSObject {
 
     // MARK: Dependencies
 
+    var proximityMonitoringManager: OWSProximityMonitoringManager {
+        return Environment.shared.proximityMonitoringManager
+    }
+
     private let avAudioSession = AVAudioSession.sharedInstance()
 
     private let device = UIDevice.current
@@ -65,30 +69,7 @@ public class OWSAudioSession: NSObject {
         self.currentActivities.append(Weak(value: audioActivity))
 
         do {
-            if aggregateBehaviors.contains(.call) {
+            try ensureAudioCategory()
-                // Do nothing while on a call.
-                // WebRTC/CallAudioService manages call audio
-                // Eventually it would be nice to consolidate more of the audio
-                // session handling.
-            } else {
-                if aggregateBehaviors.contains(.playAndRecord) {
-                    assert(avAudioSession.recordPermission() == .granted)
-                    try avAudioSession.setCategory(AVAudioSessionCategoryRecord)
-                } else if aggregateBehaviors.contains(.audioMessagePlayback) {
-                    try ensureCategoryForProximityState()
-                } else if aggregateBehaviors.contains(.playback) {
-                    try avAudioSession.setCategory(AVAudioSessionCategoryPlayback)
-                } else {
-                    owsFailDebug("no category option specified. Leaving category untouched.")
-                }
-
-                if aggregateBehaviors.contains(.audioMessagePlayback) {
-                    self.device.isProximityMonitoringEnabled = true
-                } else {
-                    self.device.isProximityMonitoringEnabled = false
-                }
-            }
-
             return true
         } catch {
             owsFailDebug("failed with error: \(error)")
@@ -97,16 +78,36 @@ public class OWSAudioSession: NSObject {
     }
 
     @objc
-    func proximitySensorStateDidChange(notification: Notification) {
+    public func endAudioActivity(_ audioActivity: AudioActivity) {
+        Logger.debug("with audioActivity: \(audioActivity)")
+
+        objc_sync_enter(self)
+        defer { objc_sync_exit(self) }
+
+        currentActivities = currentActivities.filter { return $0.value != audioActivity }
         do {
-            try ensureCategoryForProximityState()
+            try ensureAudioCategory()
         } catch {
-            owsFailDebug("error in response to proximity change: \(error)")
+            owsFailDebug("error in ensureAudioCategory: \(error)")
         }
     }
 
-    func ensureCategoryForProximityState() throws {
+    func ensureAudioCategory() throws {
         if aggregateBehaviors.contains(.audioMessagePlayback) {
+            self.proximityMonitoringManager.add(lifetime: self)
+        } else {
+            self.proximityMonitoringManager.remove(lifetime: self)
+        }
+
+        if aggregateBehaviors.contains(.call) {
+            // Do nothing while on a call.
+            // WebRTC/CallAudioService manages call audio
+            // Eventually it would be nice to consolidate more of the audio
+            // session handling.
+        } else if aggregateBehaviors.contains(.playAndRecord) {
+            assert(avAudioSession.recordPermission() == .granted)
+            try avAudioSession.setCategory(AVAudioSessionCategoryRecord)
+        } else if aggregateBehaviors.contains(.audioMessagePlayback) {
             if self.device.proximityState {
                 Logger.debug("proximityState: true")
 
@@ -116,23 +117,20 @@ public class OWSAudioSession: NSObject {
                 Logger.debug("proximityState: false")
                 try avAudioSession.setCategory(AVAudioSessionCategoryPlayback)
             }
+        } else if aggregateBehaviors.contains(.playback) {
+            try avAudioSession.setCategory(AVAudioSessionCategoryPlayback)
+        } else {
+            ensureAudioSessionActivationStateAfterDelay()
         }
     }
 
     @objc
-    public func endAudioActivity(_ audioActivity: AudioActivity) {
+    func proximitySensorStateDidChange(notification: Notification) {
-        Logger.debug("with audioActivity: \(audioActivity)")
-
-        objc_sync_enter(self)
-        defer { objc_sync_exit(self) }
-
-        currentActivities = currentActivities.filter { return $0.value != audioActivity }
         do {
-            try ensureCategoryForProximityState()
+            try ensureAudioCategory()
         } catch {
-            owsFailDebug("error in ensureProximityState: \(error)")
+            owsFailDebug("error in response to proximity change: \(error)")
         }
-        ensureAudioSessionActivationStateAfterDelay()
     }
 
     fileprivate func ensureAudioSessionActivationStateAfterDelay() {

SignalMessaging/utils/ProximityMonitoringManager.swift

@@ -0,0 +1,55 @@
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
+
+@objc
+public protocol OWSProximityMonitoringManager: class {
+    func add(lifetime: AnyObject)
+    func remove(lifetime: AnyObject)
+}
+
+@objc
+public class OWSProximityMonitoringManagerImpl: NSObject, OWSProximityMonitoringManager {
+    var lifetimes: [Weak<AnyObject>] = []
+    let serialQueue = DispatchQueue(label: "ProximityMonitoringManagerImpl")
+
+    // MARK: 
+
+    var device: UIDevice {
+        return UIDevice.current
+    }
+
+    // MARK: 
+
+    @objc
+    public func add(lifetime: AnyObject) {
+        serialQueue.sync {
+            if !lifetimes.contains { $0.value === lifetime } {
+                lifetimes.append(Weak(value: lifetime))
+            }
+            reconcile()
+        }
+    }
+
+    @objc
+    public func remove(lifetime: AnyObject) {
+        serialQueue.sync {
+            lifetimes = lifetimes.filter { $0.value !== lifetime }
+            reconcile()
+        }
+    }
+
+    func reconcile() {
+        if _isDebugAssertConfiguration() {
+            assertOnQueue(serialQueue)
+        }
+        lifetimes = lifetimes.filter { $0.value != nil }
+        if lifetimes.isEmpty {
+            Logger.debug("disabling proximity monitoring")
+            device.isProximityMonitoringEnabled = false
+        } else {
+            Logger.debug("enabling proximity monitoring for lifetimes: \(lifetimes)")
+            device.isProximityMonitoringEnabled = true
+        }
+    }
+}