multipeer-connectivity

name: multipeer-connectivity description: Expert in MultipeerConnectivity and the RemoteCmd message protocol. Use when working with peer-to-peer communication, NSCoding serialization, adding new remote commands, or debugging connection issues. allowed-tools: Read, Grep, Glob, Edit, Write

MultipeerConnectivity & Remote Commands Expert

Context

Remote Shutter uses Apple's MultipeerConnectivity framework (service type: "RemoteCam") for peer-to-peer communication between camera and monitor devices.

Message Protocol

RemoteCmd (RemoteCmds.swift)

• Messages serialized via NSCoding and sent over MultipeerConnectivity
• Use @objc name annotations for stable serialization
• Example: @objc(_TtCC10ActorsDemo9RemoteCmd7TakePic)

UICmd (UICmds.swift)

• Local messages between actors and view controllers within a single device
• Not serialized over the network

Serialization Pattern

Messages use NSKeyedArchiver/NSKeyedUnarchiver and are sent via MCSession.send().

Adding a New Remote Command

1. Create a new class nested under RemoteCmd
2. Add @objc class name annotation for backward compatibility
3. Implement NSCoding:
   • encode(with coder: NSCoder) — Serialize properties
   • init?(coder: NSCoder) — Deserialize properties
4. Handle the command in the appropriate state handler

Large Data Transfers

• Video files use MCSession.sendResource() for large transfers
• Progress tracking is built into the resource transfer API

Rules

1. Always add @objc name annotation to new RemoteCmd subclasses
2. Always implement both encode and init?(coder:) for NSCoding
3. Use the established @objc(_TtCC10ActorsDemo9RemoteCmd_ClassName) naming pattern
4. Handle new commands in both camera and monitor state handlers
5. Test serialization round-trips for new commands