fix: update unattributed outcomes to match attributed outcomes and Android SDK

[nan-li]

Description

One Line Summary

Align iOS session duration reporting (both attributed and unattributed) with Android SDK behavior by deferring all sends behind a 30-second timer.

Details

Motivation

Previously, attributed and unattributed session processors behaved differently:

• Attributed: Sent session time to Update User on every background event with just the current interval, and deferred the outcomes/measure call behind a 30-second timer. This is so the outcome event only sends at the end of a session rather than on every background.
• Unattributed: Required 60 seconds of accumulated time before sending anything, then sent the session time to Update User (with the full total) and the outcomes/measure call immediately with no delay. This means outcomes can be sent multiple times for a single session. Analytics would be overcounted for unattributed session counts.

This caused inconsistency between attribution types and also it diverged from the Android SDK, which uses a single model: send both the user property update and the outcomes call together once after a 30-second timer confirms the user has left the app, with no minimum accumulation time required.

Scope

What changed:

OSUnattributedFocusTimeProcessor:

• Added a 30-second NSTimer delay before sending to outcomes/measure (matching attributed)
• Sends immediately (no delay) when a session ends via influence change (onSessionEnded)
• Implemented cancelDelayedJob to invalidate the timer when the user returns to foreground within 30 seconds
• Moved sendSessionTime from sendOnFocusCall: to the final send method, so it fires once with the full accumulated total (not on every background)
• Removed the 60-second minimum accumulation threshold
• Unsent time is now only cleared on outcomes success (retried on next open if it fails)

OSAttributedFocusTimeProcessor:

• Moved sendSessionTime from sendOnFocusCall: to sendBackgroundAttributedSessionTimeWithParams:, so it fires once with the full accumulated total when the 30-second timer fires or the session ends

Resulting behavior (same for both attributed and unattributed)

1. User backgrounds the app → time interval is accumulated and persisted, no network calls
2. If user returns within 30 seconds → timer is cancelled, accumulation continues on next background
3. If 30 seconds pass in background → both sendSessionTime (user property update) and outcomes/measure are sent together with the full accumulated session total
4. If session ends due to influence change → both calls are sent immediately with the full accumulated total

Testing

Unit testing

Manual testing

Tested attributed and unattributed session flows by foregrounding/backgrounding the app and verifying:

• No network calls on background events within 30 seconds
• Both sendSessionTime and outcomes/measure fire together after 30 seconds with the correct accumulated total
• Timer is cancelled and no calls are made when returning within 30 seconds
• Immediate send when session ends due to influence change

Affected code checklist

• Notifications
  • Display
  • Open
  • Push Processing
  • Confirm Deliveries
• Outcomes
• Sessions
• In-App Messaging
• REST API requests
• Public API changes

Checklist

Overview

• I have filled out all REQUIRED sections above
• PR does one thing
• Any Public API changes are explained in the PR details and conform to existing APIs

Testing

• I have included test coverage for these changes, or explained why they are not needed
• All automated tests pass, or I explained why that is not possible
• I have personally tested this on my device, or explained why that is not possible

Final pass

• Code is as readable as possible.
• I have reviewed this PR myself, ensuring it meets each checklist item