[ECO-5496] Remove throwing handler

[maratal]

Closes #344

Summary by CodeRabbit

• Bug Fixes

  • Prevents potential retain cycles in presence event subscriptions, reducing risk of memory leaks and improving app stability.

• Refactor

  • Streamlined presence subscription callbacks to use a safer capture pattern.
  • Unified handling for single and multiple event subscriptions.
  • Simplified internal error handling without changing behavior or public APIs.

[coderabbitai]

Walkthrough

Converted presence subscription closures to capture weak self, removed try/catch handling, and made processPresenceSubscribe non-throwing. Updated single- and multi-event subscription paths accordingly. No changes to public APIs or other presence behaviors.

Changes

Cohort / File(s)	Summary of Changes
Presence subscriptions refactor Sources/AblyChat/DefaultPresence.swift	- Closures capture weak self; early-exit if deallocated - Removed try/catch around processing; direct invocation - Changed helper to non-throwing: processPresenceSubscribe(_:for:) -> PresenceEvent - Applied same pattern to single/multi-event subscriptions; logging retained

Sequence Diagram(s)

sequenceDiagram
  participant Client
  participant AblySDK as Ably SDK
  participant DefaultPresence
  participant Callback

  Client->>AblySDK: subscribe(presence events)
  AblySDK-->>DefaultPresence: PresenceMessage(event)
  DefaultPresence->>DefaultPresence: processPresenceSubscribe(message, event) // non-throwing
  DefaultPresence-->>Callback: callback(PresenceEvent)

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Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Assessment against linked issues

Objective	Addressed	Explanation
Remove throwing in presence subscription handler (#344, ECO-5496)	✅

Assessment against linked issues: Out-of-scope changes

[No out-of-scope functional changes detected.]

Possibly related issues

• Avoid strong reference cycle by not capturing self through method reference #287 — Implements the same weak-self capture and non-throwing processing in DefaultPresence.subscribe paths.

Poem

In burrows of code where callbacks hop,
I snip the throws—a gentle plop.
Weak little self peeks out to see,
“Am I alive? Then let it be.”
Presence events now glide with ease—
No tangled nets, just breezy breeze. 🐇✨

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Actionable comments posted: 2

📜 Review details

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📥 Commits

Reviewing files that changed from the base of the PR and between abed8e1 and d777a43.

📒 Files selected for processing (1)

• Sources/AblyChat/DefaultPresence.swift (3 hunks)

🧰 Additional context used

🧠 Learnings (5)

📓 Common learnings

Learnt from: maratal
PR: ably/ably-chat-swift#286
File: Sources/AblyChat/DefaultTyping.swift:131-138
Timestamp: 2025-05-12T21:04:36.263Z
Learning: In the AblyChat Swift codebase, SubscriptionHandle closures should capture self weakly with `[weak self]` to avoid potential retain cycles, particularly when calling channel.unsubscribe() within the closure.

Learnt from: maratal
PR: ably/ably-chat-swift#286
File: Sources/AblyChat/RoomLifecycleManager.swift:611-624
Timestamp: 2025-05-22T20:57:48.147Z
Learning: In AblyChat Swift, when using continuations with subscription callbacks, the continuation object is captured directly by the closure and doesn't depend on `self`. Even with `[weak self]` capture, the continuation will still be resumed properly.

📚 Learning: 2025-05-12T21:04:36.263Z

Learnt from: maratal
PR: ably/ably-chat-swift#286
File: Sources/AblyChat/DefaultTyping.swift:131-138
Timestamp: 2025-05-12T21:04:36.263Z
Learning: In the AblyChat Swift codebase, SubscriptionHandle closures should capture self weakly with `[weak self]` to avoid potential retain cycles, particularly when calling channel.unsubscribe() within the closure.

Applied to files:

• Sources/AblyChat/DefaultPresence.swift

📚 Learning: 2025-05-22T20:57:48.147Z

Learnt from: maratal
PR: ably/ably-chat-swift#286
File: Sources/AblyChat/RoomLifecycleManager.swift:611-624
Timestamp: 2025-05-22T20:57:48.147Z
Learning: In AblyChat Swift, when using continuations with subscription callbacks, the continuation object is captured directly by the closure and doesn't depend on `self`. Even with `[weak self]` capture, the continuation will still be resumed properly.

Applied to files:

• Sources/AblyChat/DefaultPresence.swift

📚 Learning: 2025-05-23T16:29:39.712Z

Learnt from: maratal
PR: ably/ably-chat-swift#262
File: Tests/AblyChatTests/DefaultRoomReactionsTests.swift:0-0
Timestamp: 2025-05-23T16:29:39.712Z
Learning: In the ably-chat-swift project, MockRealtimeChannel processes messages synchronously when subscribe is called, immediately delivering the configured messages to the callback.

Applied to files:

• Sources/AblyChat/DefaultPresence.swift

📚 Learning: 2025-05-12T21:11:08.937Z

Learnt from: maratal
PR: ably/ably-chat-swift#286
File: Example/AblyChatExample/ContentView.swift:203-209
Timestamp: 2025-05-12T21:11:08.937Z
Learning: In the AblyChat Swift codebase, SubscriptionHandle doesn't need to be retained/stored to keep subscriptions active. The subscription callbacks continue to work even when the handle is not stored, as the underlying services maintain their own storage of callbacks that remain registered until explicitly unsubscribed via the handle's unsubscribe() method.

Applied to files:

• Sources/AblyChat/DefaultPresence.swift

🧬 Code Graph Analysis (1)

Sources/AblyChat/DefaultPresence.swift (2)

Sources/AblyChat/Presence.swift (5)

• subscribe (137-151)
• subscribe (164-178)
• subscribe (181-183)
• subscribe (186-188)
• toARTPresenceAction (244-255)

Sources/AblyChat/DefaultOccupancy.swift (1)

• subscribe (20-58)

🔇 Additional comments (1)

Sources/AblyChat/DefaultPresence.swift (1)

264-279: Non-throwing processing helper aligns with PR objective.

processPresenceSubscribe is now non-throwing and returns a PresenceEvent directly. This matches the goal of removing throwing behavior from the subscription path. Implementation is straightforward and logs appropriately.