Remove nullability of -subscribe* return value

[lawrence-forooghian]

There’s no reason for these to be nullable (it just makes it harder to call the -unsubscribe methods, which take a nonnull listener), and the return type of the underlying methods is nonnull.

Summary by CodeRabbit

• Type Safety Improvements

  • Updated method signatures in ARTRealtimeChannel and ARTRealtimePresence to ensure non-nullable event listener returns.
  • Removed nullable return types for subscription methods to enhance code robustness.

• New Method

  • Added newWithPresenceSyncState: class method to ARTEvent.

• Test Enhancements

  • Improved safety in presence listener tests by removing forced unwrapping of listeners.

The changes focus on improving type safety and method consistency across the Ably realtime channel and presence APIs.

[coderabbitai]

Warning

There were issues while running some tools. Please review the errors and either fix the tool’s configuration or disable the tool if it’s a critical failure.

🔧 SwiftLint (0.57.0)

Test/Tests/RealtimeClientPresenceTests.swift

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Walkthrough

The pull request involves systematic modifications to method signatures across multiple Objective-C files in the Ably SDK. The primary change is updating the return type of various subscribe methods in ARTRealtimeChannel and ARTRealtimePresence classes from ARTEventListener *_Nullable to ARTEventListener *. This modification ensures that these methods always return a non-nullable event listener, enhancing type safety and potentially simplifying error handling in the codebase. Additionally, a new method for instantiating ARTEvent with a specific presence sync state has been introduced.

Changes

File	Changes
Source/ARTRealtimeChannel.m	Updated return types for multiple subscribe methods from _Nullable to non-nullable
Source/ARTRealtimePresence.m	Updated return types for multiple subscribe methods from _Nullable to non-nullable; Added new class method + (instancetype)newWithPresenceSyncState: to ARTEvent
Source/include/Ably/ARTRealtimeChannel.h	Updated method signatures in ARTRealtimeChannelProtocol to remove nullability
Source/include/Ably/ARTRealtimePresence.h	Updated method signatures in ARTRealtimePresenceProtocol to remove nullability
Test/Tests/RealtimeClientPresenceTests.swift	Removed forced unwrapping from listener assignments in test methods to enhance safety

Poem

🐰 Hop, hop, through the code we go,
Nullable types, now they're set to flow!
No more question marks in our sight,
Listeners return, clean and bright!
A rabbit's leap of type safety's might! 🚀

---

📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 7c8eceb and cb143de.

📒 Files selected for processing (5)

• Source/ARTRealtimeChannel.m (1 hunks)
• Source/ARTRealtimePresence.m (1 hunks)
• Source/include/Ably/ARTRealtimeChannel.h (4 hunks)
• Source/include/Ably/ARTRealtimePresence.h (4 hunks)
• Test/Tests/RealtimeClientPresenceTests.swift (2 hunks)

🚧 Files skipped from review as they are similar to previous changes (4)

• Source/ARTRealtimeChannel.m
• Source/include/Ably/ARTRealtimeChannel.h
• Source/include/Ably/ARTRealtimePresence.h
• Source/ARTRealtimePresence.m

⏰ Context from checks skipped due to timeout of 90000ms (6)

• GitHub Check: check (macOS, test_macOS)
• GitHub Check: check (tvOS, test_tvOS17_2)
• GitHub Check: check (iOS, test_iOS17_2)
• GitHub Check: check
• GitHub Check: build
• GitHub Check: check

🔇 Additional comments (3)

Test/Tests/RealtimeClientPresenceTests.swift (3)

500-500: Improved safety by removing force unwrapping

The removal of force unwrapping (!) from the listener assignment makes the code safer, as it aligns with the updated API where subscribe now returns a non-nullable ARTEventListener.

---

881-881: Improved safety by removing force unwrapping

Similarly, the removal of force unwrapping (!) from the action-specific subscription makes the code safer, as it aligns with the updated API where subscribe(.present) now returns a non-nullable ARTEventListener.

---

Line range hint 500-881: Verify test coverage for subscription error cases

While the changes improve safety by removing force unwrapping, it would be good to add test cases that verify error handling when subscriptions fail.

---

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