[codex] Add iOS BLE central background restore shim

build-qdomyos-zwift-Qt_5_15_2_for_iOS-Debug/qdomyoszwift.xcodeproj/project.pbxproj

@@ -131,6 +131,8 @@
 		870A5DB32CEF8FB100839641 /* moc_technogymbike.cpp in Compile Sources */ = {isa = PBXBuildFile; fileRef = 870A5DB22CEF8FB100839641 /* moc_technogymbike.cpp */; };
 		870A5DB52CEF8FD200839641 /* technogymbike.cpp in Compile Sources */ = {isa = PBXBuildFile; fileRef = 870A5DB42CEF8FD200839641 /* technogymbike.cpp */; };
 		870C72652E91565E00DC8A84 /* ios_liveactivity.mm in Compile Sources */ = {isa = PBXBuildFile; fileRef = 870C72632E91565E00DC8A84 /* ios_liveactivity.mm */; };
+		87BA10032F0000010000BA03 /* ios_background_keepalive.mm in Compile Sources */ = {isa = PBXBuildFile; fileRef = 87BA10022F0000010000BA02 /* ios_background_keepalive.mm */; };
+		87BA10052F0000010000BA05 /* ios_bluetooth_background.mm in Compile Sources */ = {isa = PBXBuildFile; fileRef = 87BA10042F0000010000BA04 /* ios_bluetooth_background.mm */; };
 		870F72D62FDEC0FD00181280 /* webtranslation.cpp in Compile Sources */ = {isa = PBXBuildFile; fileRef = 870F72D52FDEC0FD00181280 /* webtranslation.cpp */; };
 		8710706C29C48AEA0094D0F3 /* handleurl.cpp in Compile Sources */ = {isa = PBXBuildFile; fileRef = 8710706B29C48AEA0094D0F3 /* handleurl.cpp */; };
 		8710706E29C48AF30094D0F3 /* moc_handleurl.cpp in Compile Sources */ = {isa = PBXBuildFile; fileRef = 8710706D29C48AF30094D0F3 /* moc_handleurl.cpp */; };
@@ -1024,6 +1026,9 @@
 		870A5DB42CEF8FD200839641 /* technogymbike.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; name = technogymbike.cpp; path = ../src/devices/technogymbike/technogymbike.cpp; sourceTree = SOURCE_ROOT; };
 		870C72622E91565E00DC8A84 /* ios_liveactivity.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = ios_liveactivity.h; path = ../src/ios/ios_liveactivity.h; sourceTree = SOURCE_ROOT; };
 		870C72632E91565E00DC8A84 /* ios_liveactivity.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; name = ios_liveactivity.mm; path = ../src/ios/ios_liveactivity.mm; sourceTree = SOURCE_ROOT; };
+		87BA10012F0000010000BA01 /* ios_background_keepalive.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; name = ios_background_keepalive.h; path = ../src/ios/ios_background_keepalive.h; sourceTree = SOURCE_ROOT; };
+		87BA10022F0000010000BA02 /* ios_background_keepalive.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; name = ios_background_keepalive.mm; path = ../src/ios/ios_background_keepalive.mm; sourceTree = SOURCE_ROOT; };
+		87BA10042F0000010000BA04 /* ios_bluetooth_background.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; name = ios_bluetooth_background.mm; path = ../src/ios/ios_bluetooth_background.mm; sourceTree = SOURCE_ROOT; };
 		870F72D52FDEC0FD00181280 /* webtranslation.cpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.cpp; name = webtranslation.cpp; path = ../src/webtranslation.cpp; sourceTree = SOURCE_ROOT; };
 		8710706A29C48AE90094D0F3 /* handleurl.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = handleurl.h; path = ../src/handleurl.h; sourceTree = "<group>"; };
 		8710706B29C48AEA0094D0F3 /* handleurl.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; name = handleurl.cpp; path = ../src/handleurl.cpp; sourceTree = "<group>"; };
@@ -2425,6 +2430,9 @@
 				87EFC57C2E918DAA005BB573 /* LiveActivityBridge.swift */,
 				870C72622E91565E00DC8A84 /* ios_liveactivity.h */,
 				870C72632E91565E00DC8A84 /* ios_liveactivity.mm */,
+				87BA10012F0000010000BA01 /* ios_background_keepalive.h */,
+				87BA10022F0000010000BA02 /* ios_background_keepalive.mm */,
+				87BA10042F0000010000BA04 /* ios_bluetooth_background.mm */,
 				876C646E2E74139F00F1BEC0 /* fitbackupwriter.h */,
 				876C646F2E74139F00F1BEC0 /* fitbackupwriter.cpp */,
 				876C64702E74139F00F1BEC0 /* moc_fitbackupwriter.cpp */,
@@ -3790,6 +3798,8 @@
 			buildActionMask = 2147483647;
 			files = (
 				870C72652E91565E00DC8A84 /* ios_liveactivity.mm in Compile Sources */,
+				87BA10032F0000010000BA03 /* ios_background_keepalive.mm in Compile Sources */,
+				87BA10052F0000010000BA05 /* ios_bluetooth_background.mm in Compile Sources */,
 				8738249627E646E3004F1B46 /* characteristicnotifier2acd.cpp in Compile Sources */,
 				8738249127E646E3004F1B46 /* dirconpacket.cpp in Compile Sources */,
 				870A5DB52CEF8FD200839641 /* technogymbike.cpp in Compile Sources */,

src/homeform.cpp

@@ -4,6 +4,7 @@
 #ifdef Q_OS_IOS
 #include "ios/lockscreen.h"
 #include "ios/ios_liveactivity.h"
+#include "ios/ios_background_keepalive.h"
 #endif
 #include "localipaddress.h"
 #ifdef Q_OS_ANDROID
@@ -5760,6 +5761,11 @@ void homeform::Start_inner(bool send_event_to_device) {
     } else {
 #ifdef Q_OS_IOS
 #ifndef IO_UNDER_QT
+        // keep the process alive (and so every QTimer and every BLE connection)
+        // when the user locks the screen during the session
+        if (settings.value(QZSettings::ios_background_keepalive, QZSettings::default_ios_background_keepalive)
+                .toBool())
+            iosBackgroundKeepAlive::start();
         if(h && !h->appleWatchAppInstalled() && bluetoothManager->device())
             h->startWorkout(bluetoothManager->device()->deviceType());
 #endif
@@ -5879,6 +5885,7 @@ void homeform::Stop() {
         h->stopWorkout();
     // End iOS Live Activity when workout stops
     ios_liveactivity::endLiveActivity();
+    iosBackgroundKeepAlive::stop();
 #endif
 #endif
 
@@ -6077,12 +6084,10 @@ void homeform::update() {
     // Timer jitter detection (same logic as trainprogram::scheduler)
     QDateTime now = QDateTime::currentDateTime();
     qint64 msecsElapsed = lastUpdateCall.msecsTo(now);
-
-    // Reset jitter if it's getting too large
-    if (qAbs(currentUpdateJitter) > 5000) {
-        currentUpdateJitter = 0;
+    if (msecsElapsed < 0) {
+        msecsElapsed = 0;
     }
-    
+
     currentUpdateJitter += msecsElapsed - 1000;
     lastUpdateCall = now;
 
@@ -8548,50 +8553,38 @@ void homeform::update() {
                 currentUpdateJitter = 0;
             }
 
-            // Check for timer jitter gaps and fill missing SessionLine records (same logic as trainprogram)
-            if (!Session.empty() && qAbs(currentUpdateJitter) > 1000) {
-                if (currentUpdateJitter > 1000) {
-                    // We are late... fill the missing seconds with SessionLine records
-                    int missedSeconds = currentUpdateJitter / 1000;
+            if (!Session.empty() && currentUpdateJitter > 1000) {
+                const uint32_t lastRecordedTime = Session.last().elapsedTime;
+                const uint32_t elapsedGap = currentElapsedSeconds > lastRecordedTime
+                    ? currentElapsedSeconds - lastRecordedTime - 1
+                    : 0;
+                const int missedSeconds = qMin<int>(currentUpdateJitter / 1000, elapsedGap);
+
+                if (missedSeconds > 0) {
                     qDebug() << "Timer jitter detected: filling" << missedSeconds << "missing SessionLine records";
-
-                    // Create SessionLine records for each missed second using current device values
-                    uint32_t lastRecordedTime = Session.last().elapsedTime;
+
                     for (int i = 1; i <= missedSeconds; i++) {
                         SessionLine gapFill(
                             bluetoothManager->device()->currentSpeed().value(), inclination, distance1s,
                             watts, resistance, peloton_resistance, (uint8_t)bluetoothManager->device()->currentHeart().value(),
                             pace, cadence, bluetoothManager->device()->calories().value(),
                             bluetoothManager->device()->elevationGain().value(),
                             bluetoothManager->device()->negativeElevationGain().value(),
-                            lastRecordedTime + i,  // Fill each missing second
+                            lastRecordedTime + i,
                             lapTrigger, totalStrokes, avgStrokesRate, maxStrokesRate, avgStrokesLength,
                             bluetoothManager->device()->currentCordinate(), strideLength, groundContact, verticalOscillation, stepCount,
                             target_cadence->value().toDouble(), target_power->value().toDouble(), target_resistance->value().toDouble(),
                             target_incline->value().toDouble(), target_speed->value().toDouble(),
                             bluetoothManager->device()->CoreBodyTemperature.value(), bluetoothManager->device()->SkinTemperature.value(), bluetoothManager->device()->HeatStrainIndex.value(),
                             0.0, QList<double>());
-                        
+
                         Session.append(gapFill);
-                        qDebug() << "Added gap-filling SessionLine for elapsed time:" << (lastRecordedTime + i);
-                    }
-
-                    // Adjust jitter counter (same as trainprogram)
-                    currentUpdateJitter -= (missedSeconds * 1000);
-                } else if (currentUpdateJitter < -1000) {
-                    // We are early (negative jitter)... remove excess SessionLine records
-                    int excessSeconds = (-currentUpdateJitter) / 1000;
-                    qDebug() << "Negative timer jitter detected: removing" << excessSeconds << "excess SessionLine records";
-
-                    // Remove excess SessionLine records from the end
-                    for (int i = 0; i < excessSeconds && !Session.empty(); i++) {
-                        Session.removeLast();
-                        qDebug() << "Removed excess SessionLine record";
                     }
-
-                    // Adjust jitter counter (same as trainprogram)
-                    currentUpdateJitter += (excessSeconds * 1000);
                 }
+
+                currentUpdateJitter %= 1000;
+            } else if (currentUpdateJitter < -1000) {
+                currentUpdateJitter %= 1000;
             }
 
             SessionLine s(

src/ios/Info.plist

@@ -83,6 +83,7 @@
 	<string>access to step cadence in order to show it on the iphone</string>
 	<key>UIBackgroundModes</key>
 	<array>
+		<string>audio</string>
 		<string>bluetooth-central</string>
 		<string>bluetooth-peripheral</string>
 	</array>

src/ios/LiveActivityBridge.swift

@@ -15,8 +15,11 @@ import UIKit
     private var currentActivity: Activity<QZWorkoutAttributes>?
     private var inactivityTimer: Timer?
 
-    // Timeout in seconds - if no updates received, auto-close the Live Activity
-    private let inactivityTimeout: TimeInterval = 10.0
+    // Timeout in seconds - if no updates received, auto-close the Live Activity.
+    // While QZ is in background the updates are throttled to one every 5 seconds
+    // (see ios_liveactivity.mm), so this has to leave a comfortable margin or a
+    // single late BLE notification would close the Live Activity.
+    private let inactivityTimeout: TimeInterval = 30.0
 
     // MARK: - Private Methods
 

src/ios/ios_app_delegate.mm

@@ -70,6 +70,14 @@ @implementation QIOSApplicationDelegate (QZApplicationDelegate)
 - (BOOL)application:(UIApplication *)application
     didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
     qDebug() << "QZ iOS launch";
+
+    // when CoreBluetooth state restoration is in place iOS can relaunch us in
+    // background to deliver a BLE event: useful to know it while reading a log
+    NSArray *restoredCentrals = [launchOptions objectForKey:UIApplicationLaunchOptionsBluetoothCentralsKey];
+    if (restoredCentrals.count > 0) {
+        qDebug() << "QZ iOS launch: relaunched by CoreBluetooth for" << (int)restoredCentrals.count << "central(s)";
+    }
+
     UNUserNotificationCenter* center = [UNUserNotificationCenter currentNotificationCenter];
     [center requestAuthorizationWithOptions:UNAuthorizationOptionBadge
       completionHandler:^(BOOL granted, NSError *error){
@@ -94,6 +102,19 @@ - (void)applicationDidBecomeActive:(UIApplication *)application {
     qDebug() << "QZ iOS lifecycle: applicationDidBecomeActive";
 }
 
+- (void)applicationWillResignActive:(UIApplication *)application {
+    Q_UNUSED(application)
+    qDebug() << "QZ iOS lifecycle: applicationWillResignActive";
+}
+
+- (void)applicationDidEnterBackground:(UIApplication *)application {
+    // With the background keep alive running the app stays in the "background"
+    // state instead of being suspended, so every QTimer (homeform::update, the
+    // per device refresh timers) and the BLE connections keep working.
+    qDebug() << "QZ iOS lifecycle: applicationDidEnterBackground, remaining background time"
+             << application.backgroundTimeRemaining;
+}
+
 - (void)pressesBegan:(NSSet<UIPress *> *)presses withEvent:(UIPressesEvent *)event {
     bool didHandleShortcut = false;
 

src/ios/ios_background_keepalive.h

@@ -0,0 +1,38 @@
+#ifndef IOS_BACKGROUND_KEEPALIVE_H
+#define IOS_BACKGROUND_KEEPALIVE_H
+
+/**
+ * @brief Keeps the app running while the screen is off / the app is in background.
+ *
+ * The `bluetooth-central` background mode alone is not enough: iOS suspends the
+ * process a few seconds after the screen goes off and only resumes it for short
+ * windows when a BLE notification arrives.  While suspended every QTimer stops,
+ * so homeform::update() and the per-device refresh timers do not run and the
+ * session is effectively frozen.
+ *
+ * Playing an (inaudible) looping buffer on an active AVAudioSession keeps the
+ * app in the "running in background" state, exactly like the background
+ * execution plugins used on Flutter.  The session is configured with
+ * MixWithOthers so the user's music/podcast is never interrupted.
+ */
+class iosBackgroundKeepAlive {
+  public:
+    /**
+     * @brief Activates the audio session and starts the silent loop.
+     * Must be called while the app is in foreground (iOS refuses to activate a
+     * new audio session from background).  Calling it twice is a no-op.
+     */
+    static void start();
+
+    /**
+     * @brief Stops the silent loop and deactivates the audio session.
+     */
+    static void stop();
+
+    /**
+     * @brief True when the keep alive loop is currently playing.
+     */
+    static bool isRunning();
+};
+
+#endif // IOS_BACKGROUND_KEEPALIVE_H