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Stop AlarmKit alarms after a relaunch #2590

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Merged
ps2 merged 1 commit into from
Oct 17, 2026
Merged

Stop AlarmKit alarms after a relaunch #2590

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38 changes: 25 additions & 13 deletions Loop/Managers/Alerts/CriticalAlertAlarmScheduler.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,7 @@
// callers fall back to CriticalAlertAudioPlayer.
//

import CryptoKit
import Foundation
import LoopKit
import os.log
Expand All @@ -29,9 +30,15 @@ import struct SwiftUI.Color // Color only; `import SwiftUI` would make `Alert`
final class CriticalAlertAlarmScheduler {
private let log = OSLog(subsystem: "com.loopkit.Loop", category: "CriticalAlertAlarmScheduler")

/// Maps an issued alert to the AlarmKit alarm scheduled for it, so the
/// alarm can be cancelled when the alert is acknowledged or retracted.
private var alarmsByAlert: [Alert.Identifier: UUID] = [:]
/// The AlarmKit alarm ID for an alert, derived from the alert identifier so
/// a relaunched app can still stop an alarm scheduled by an earlier process.
static func alarmID(for identifier: Alert.Identifier) -> UUID {
var bytes = Array(SHA256.hash(data: Data("\(identifier.managerIdentifier).\(identifier.alertIdentifier)".utf8)).prefix(16))
bytes[6] = (bytes[6] & 0x0F) | 0x50
bytes[8] = (bytes[8] & 0x3F) | 0x80
return UUID(uuid: (bytes[0], bytes[1], bytes[2], bytes[3], bytes[4], bytes[5], bytes[6], bytes[7],
bytes[8], bytes[9], bytes[10], bytes[11], bytes[12], bytes[13], bytes[14], bytes[15]))
}

/// Whether the user has allowed alarms. nil where AlarmKit doesn't exist (below iOS 26).
static var alarmsAuthorized: Bool? {
Expand Down Expand Up @@ -118,17 +125,15 @@ final class CriticalAlertAlarmScheduler {
sound: sound
)

let id = UUID()
alarmsByAlert[alert.identifier] = id
let id = Self.alarmID(for: alert.identifier)
let log = self.log
let identifier = alert.identifier
Task { [weak self] in
Task {
do {
_ = try await AlarmManager.shared.schedule(id: id, configuration: configuration)
os_log("Scheduled AlarmKit alarm %{public}@ for %{public}@", log: log, type: .info, id.uuidString, String(describing: identifier))
} catch {
os_log("Failed to schedule AlarmKit alarm for %{public}@: %{public}@ — falling back to audio", log: log, type: .error, String(describing: identifier), String(describing: error))
self?.alarmsByAlert.removeValue(forKey: identifier)
onScheduleFailure()
}
}
Expand All @@ -142,12 +147,19 @@ final class CriticalAlertAlarmScheduler {
func cancelAlarm(for identifier: Alert.Identifier) {
guard #available(iOS 26, *) else { return }
#if canImport(AlarmKit)
guard let id = alarmsByAlert.removeValue(forKey: identifier) else { return }
// stop() ends a ringing alarm; cancel() removes a scheduled one. The
// alarm may be in either state, so try both and ignore errors.
try? AlarmManager.shared.stop(id: id)
try? AlarmManager.shared.cancel(id: id)
os_log("Cancelled AlarmKit alarm %{public}@ for %{public}@", log: log, type: .info, id.uuidString, String(describing: identifier))
let id = Self.alarmID(for: identifier)
do {
guard let alarm = try AlarmManager.shared.alarms.first(where: { $0.id == id }) else { return }
// stop() ends a ringing alarm; cancel() removes a scheduled one
if alarm.state == .alerting {
try AlarmManager.shared.stop(id: id)
} else {
try AlarmManager.shared.cancel(id: id)
}
os_log("Cancelled AlarmKit alarm %{public}@ for %{public}@", log: log, type: .info, id.uuidString, String(describing: identifier))
} catch {
os_log("Failed to cancel AlarmKit alarm %{public}@ for %{public}@: %{public}@", log: log, type: .error, id.uuidString, String(describing: identifier), String(describing: error))
}
#endif
}
}
Expand Down