tools-only 09 DeviceActivity Scheduling Thresholds and Errors
Purpose
Define schedule/event modeling with explicit limits and error handling requirements.
Canonical API Surface
DeviceActivityCenter.startMonitoring(_:during:events:)DeviceActivityScheduleDeviceActivityEventDeviceActivityCenter.MonitoringError
Implementation Pattern
- Build schedule windows from deterministic date components.
- Use named
DeviceActivityNameconstants to avoid collisions. - Include threshold events only when required.
- Handle
MonitoringErrorwith user-visible and telemetry-visible paths. - Use fallback schedule when detailed monitor setup fails.
MonitoringError Handling Matrix
.excessiveActivities: reduce monitor count and consolidate schedules..intervalTooShort: enforce minimum 15-minute intervals..intervalTooLong: enforce one-week cap for event monitoring intervals..invalidDateComponents: validate schedule components before registration..unauthorized: request/recover FamilyControls authorization.
Failure Modes
- Attempting >20 simultaneous monitored activities.
- Non-unique activity names.
- Too granular intervals causing runtime throws.
- Ignoring timezone behavior at interval boundaries.
Validation Checklist
- Interval bounds validated pre-registration.
- Activity names are unique.
- Start-monitoring exceptions are surfaced and logged.
- Fallback schedule path tested.
- Time-zone change scenario tested.
Sources
../evidence/04-deviceactivity-sdk-signatures.md- https://developer.apple.com/documentation/deviceactivity/deviceactivitycenter/startmonitoring(_:during:events:)
- https://developer.apple.com/documentation/deviceactivity/deviceactivitycenter/monitoringerror
- https://developer.apple.com/documentation/deviceactivity/deviceactivitycenter/monitoringerror/intervaltooshort
- https://developer.apple.com/documentation/deviceactivity/deviceactivityschedule
- https://developer.apple.com/documentation/deviceactivity/deviceactivityevent
Confidence Notes
- Limits and errors are
sdk-backedand reinforced by canonical doc pages.