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Keep fullscreen apps active in background on macOS >= 15 #226
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811f004
Keep fullscreen apps active in background
Brawl345 99dc54d
Move BackgroundKeepAlive class to its own file
Brawl345 bce590a
Fix check for macOS version since it's running under iOS
Brawl345 70bdc17
Fix SwiftLint body length violation error by deduplicating some code
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,197 @@ | ||
| // | ||
| // BackgroundKeepAlive.swift | ||
| // PlayTools | ||
| // | ||
|
|
||
| import AVFoundation | ||
| import os | ||
|
|
||
| // Since macOS 15, runningboardd freezes iOS apps as soon as their scene is | ||
| // no longer visible. Like on iOS, an app that is actively playing audio is | ||
| // exempt, so keep an inaudible player running for the whole app lifetime. | ||
| // Requires "UIBackgroundModes: [audio]" in the app's Info.plist. | ||
| class BackgroundKeepAlive { | ||
| static let shared = BackgroundKeepAlive() | ||
| static let log = Logger(subsystem: "io.playcover.PlayTools", category: "BackgroundKeepAlive") | ||
|
|
||
| private let engine = AVAudioEngine() | ||
| private let player = AVAudioPlayerNode() | ||
| private var silence: AVAudioPCMBuffer? | ||
|
|
||
| // The OS legitimately moves the scene to background when it becomes | ||
| // invisible (the signal does not come from NSWindow.occlusionState, so it | ||
| // cannot be spoofed there). Games then pause themselves per the iOS | ||
| // lifecycle convention. Audio playback already prevents the OS-side | ||
| // suspension, so it is sufficient to hide the background transition from | ||
| // the app: drop the lifecycle notifications and neuter the corresponding | ||
| // app/scene delegate callbacks. | ||
| // Name is shared with AKInterface, which posts it from its | ||
| // NSApplication.terminate hook before the actual termination starts. | ||
| static let willTerminateNotification = | ||
| Notification.Name("io.playcover.PlayTools.applicationWillTerminate") | ||
|
|
||
| // Cleared once termination starts: the shutdown sequence replays exactly | ||
| // the suppressed lifecycle events (resign active, enter background) so the | ||
| // game can save its state — from that point on they must reach the app. | ||
| private static var suppressionActive = true | ||
| private var terminating = false | ||
|
|
||
| private static let suppressedNotifications: Set<String> = [ | ||
| UIApplication.willResignActiveNotification.rawValue, | ||
| UIApplication.didEnterBackgroundNotification.rawValue, | ||
| UIScene.willDeactivateNotification.rawValue, | ||
| UIScene.didEnterBackgroundNotification.rawValue | ||
| ] | ||
|
|
||
| private func suppressBackgroundLifecycle() { | ||
| Self.installPostFilter(NSSelectorFromString("postNotificationName:object:userInfo:")) | ||
| Self.installPostFilter(NSSelectorFromString("postNotification:")) | ||
|
|
||
| NotificationCenter.default.addObserver(forName: UIScene.willConnectNotification, | ||
| object: nil, queue: .main) { notif in | ||
| guard let scene = notif.object as? UIScene, let delegate = scene.delegate else { return } | ||
| Self.neuter(type(of: delegate), "sceneDidEnterBackground:") | ||
| Self.neuter(type(of: delegate), "sceneWillResignActive:") | ||
| } | ||
| NotificationCenter.default.addObserver(forName: UIApplication.didFinishLaunchingNotification, | ||
| object: nil, queue: .main) { _ in | ||
| guard let delegate = UIApplication.shared.delegate else { return } | ||
| Self.neuter(type(of: delegate), "applicationDidEnterBackground:") | ||
| Self.neuter(type(of: delegate), "applicationWillResignActive:") | ||
| } | ||
| } | ||
|
|
||
| private static func installPostFilter(_ selector: Selector) { | ||
| guard let method = class_getInstanceMethod(NotificationCenter.self, selector) else { return } | ||
| let originalImp = method_getImplementation(method) | ||
| if selector == NSSelectorFromString("postNotification:") { | ||
| typealias PostFn = @convention(c) (NotificationCenter, Selector, NSNotification) -> Void | ||
| let original = unsafeBitCast(originalImp, to: PostFn.self) | ||
| let block: @convention(block) (NotificationCenter, NSNotification) -> Void = { center, notif in | ||
| if suppressionActive && center === NotificationCenter.default | ||
| && suppressedNotifications.contains(notif.name.rawValue) { | ||
| log.debug("suppressed post: \(notif.name.rawValue, privacy: .public)") | ||
| return | ||
| } | ||
| original(center, selector, notif) | ||
| } | ||
| method_setImplementation(method, imp_implementationWithBlock(block)) | ||
| } else { | ||
| typealias PostNameFn = @convention(c) | ||
| (NotificationCenter, Selector, NSString, AnyObject?, NSDictionary?) -> Void | ||
| let original = unsafeBitCast(originalImp, to: PostNameFn.self) | ||
| let block: @convention(block) | ||
| (NotificationCenter, NSString, AnyObject?, NSDictionary?) -> Void = { center, name, obj, info in | ||
| if suppressionActive && center === NotificationCenter.default | ||
| && suppressedNotifications.contains(name as String) { | ||
| log.debug("suppressed postName: \(name, privacy: .public)") | ||
| return | ||
| } | ||
| original(center, selector, name, obj, info) | ||
| } | ||
| method_setImplementation(method, imp_implementationWithBlock(block)) | ||
| } | ||
| } | ||
|
|
||
| private static func neuter(_ cls: AnyClass, _ selectorName: String) { | ||
| let selector = NSSelectorFromString(selectorName) | ||
| guard let method = class_getInstanceMethod(cls, selector) else { | ||
| log.error("neuter: \(String(describing: cls), privacy: .public) has no \(selectorName, privacy: .public)") | ||
| return | ||
| } | ||
| typealias LifecycleFn = @convention(c) (AnyObject, Selector, AnyObject?) -> Void | ||
| let original = unsafeBitCast(method_getImplementation(method), to: LifecycleFn.self) | ||
| let block: @convention(block) (AnyObject, AnyObject?) -> Void = { target, arg in | ||
| if suppressionActive { | ||
| log.debug("neutered call: \(selectorName, privacy: .public)") | ||
| return | ||
| } | ||
| original(target, selector, arg) | ||
| } | ||
| method_setImplementation(method, imp_implementationWithBlock(block)) | ||
| log.notice("neutered: \(String(describing: cls), privacy: .public).\(selectorName, privacy: .public)") | ||
| } | ||
|
|
||
| // Stop hiding the background transition and release the audio exemption | ||
| // so the app can shut down cleanly. Without this, the game never receives | ||
| // its save-and-quit lifecycle events and the process lingers half-dead. | ||
| func prepareForTermination() { | ||
| guard !terminating else { return } | ||
| terminating = true | ||
| Self.suppressionActive = false | ||
| if engine.isRunning { | ||
| player.stop() | ||
| engine.stop() | ||
| } | ||
| try? AVAudioSession.sharedInstance().setActive(false) | ||
| Self.log.notice("terminating: suppression disabled, silent audio stopped") | ||
| } | ||
|
|
||
| func start() { | ||
| suppressBackgroundLifecycle() | ||
|
|
||
| // AKInterface posts this from its NSApplication.terminate hook, which | ||
| // covers Cmd+Q, the menu item and quitting from the Dock. Observe with | ||
| // queue nil so it runs synchronously before termination proceeds. | ||
| NotificationCenter.default.addObserver(forName: Self.willTerminateNotification, | ||
| object: nil, queue: nil) { [weak self] _ in | ||
| self?.prepareForTermination() | ||
| } | ||
|
|
||
| let session = AVAudioSession.sharedInstance() | ||
| do { | ||
| try session.setCategory(.playback, options: [.mixWithOthers]) | ||
| try session.setActive(true) | ||
| } catch { | ||
| Self.log.error("audio session setup failed: \(error, privacy: .public)") | ||
| } | ||
|
|
||
| guard let format = AVAudioFormat(standardFormatWithSampleRate: 44100, channels: 2), | ||
| let buffer = AVAudioPCMBuffer(pcmFormat: format, frameCapacity: 44100) else { | ||
| Self.log.error("could not create silence buffer") | ||
| return | ||
| } | ||
| buffer.frameLength = buffer.frameCapacity | ||
| if let channels = buffer.floatChannelData { | ||
| for channel in 0..<Int(format.channelCount) { | ||
| channels[channel].update(repeating: 0, count: Int(buffer.frameLength)) | ||
| } | ||
| } | ||
| silence = buffer | ||
|
|
||
| engine.attach(player) | ||
| engine.connect(player, to: engine.mainMixerNode, format: format) | ||
| engine.mainMixerNode.outputVolume = 0 | ||
|
|
||
| // The engine stops on output device changes and session interruptions; | ||
| // restart it or the suspension exemption is silently lost. | ||
| NotificationCenter.default.addObserver(forName: .AVAudioEngineConfigurationChange, | ||
| object: engine, | ||
| queue: .main) { [weak self] _ in | ||
| self?.ensureRunning() | ||
| } | ||
| NotificationCenter.default.addObserver(forName: AVAudioSession.interruptionNotification, | ||
| object: nil, | ||
| queue: .main) { [weak self] _ in | ||
| self?.ensureRunning() | ||
| } | ||
|
|
||
| ensureRunning() | ||
| } | ||
|
|
||
| private func ensureRunning() { | ||
| guard !terminating, let silence = silence else { return } | ||
| do { | ||
| if !engine.isRunning { | ||
| try engine.start() | ||
| } | ||
| if !player.isPlaying { | ||
| player.scheduleBuffer(silence, at: nil, options: .loops) | ||
| player.play() | ||
| } | ||
| Self.log.notice("silent audio running") | ||
| } catch { | ||
| Self.log.error("engine start failed: \(error, privacy: .public)") | ||
| } | ||
| } | ||
| } |
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No need for the
fileprivatemodifier since that is the default for any variable, same for the ones inextension AKPlugin.