Multipeer Connectivity框架数据发送失败：[GCKSession] 未处于连接状态问题求助

Let’s break down why you’re seeing those "not connected" errors and fix the data sending issue:

1. Don’t Trust connectedPeers Alone — Check Real-Time Peer State #

The connectedPeers array can be out of sync with the actual connection state of peers (it might show a peer as connected before the handshake fully completes). Instead, always verify a peer’s state using mcSession.state(for: peer) before sending data.

Modify your send method to filter for truly connected peers:

func sendPayData(totalUser: String) {
    // Filter peers that are actually in .connected state
    let trulyConnectedPeers = mcSession.connectedPeers.filter {
        mcSession.state(for: $0) == .connected
    }
    
    guard !trulyConnectedPeers.isEmpty else {
        print("No peers are fully connected yet")
        return
    }
    
    guard let data = totalUser.data(using: .ascii) else {
        print("Failed to convert string to ASCII data")
        return
    }
    
    do {
        try mcSession.send(data, toPeers: trulyConnectedPeers, with: .reliable)
    } catch let error as NSError {
        // Log detailed error info for debugging
        print("Send Error: Domain=\(error.domain), Code=\(error.code), Message=\(error.localizedDescription)")
        let ac = UIAlertController(title: "Send error", message: error.localizedDescription, preferredStyle: .alert)
        ac.addAction(UIAlertAction(title: "OK", style: .default))
        present(ac, animated: true)
    }
}

2. Ensure You’re Reacting to Connection State Changes #

Make sure your MCSessionDelegate properly tracks peer states, and only send data after a peer transitions to .connected:

func session(_ session: MCSession, peer peerID: MCPeerID, didChange state: MCSessionState) {
    DispatchQueue.main.async {
        switch state {
        case .connected:
            print("✅ Peer \(peerID.displayName) is fully connected and ready for data")
            // Trigger data sending here if needed, or update a local list of ready peers
        case .connecting:
            print("🔄 Peer \(peerID.displayName) is connecting...")
        case .notConnected:
            print("❌ Peer \(peerID.displayName) disconnected")
        @unknown default:
            print("❓ Unknown state for peer \(peerID.displayName)")
        }
    }
}

3. Validate Your MCSession Initialization #

Double-check how you’re initializing your MCSession — even with encryptionPreference set to .none, misconfigured security settings can break connections:

// Correct initialization for unencrypted sessions
let myPeerID = MCPeerID(displayName: UIDevice.current.name)
let mcSession = MCSession(peer: myPeerID, securityIdentity: nil, encryptionPreference: .none)
mcSession.delegate = self

If you’re passing a securityIdentity value by accident, it can cause silent connection failures even if peers appear in connectedPeers.

4. Verify MCBrowserViewController Integration #

Ensure your browser delegate is correctly handling new connections and using the same MCSession instance:

func browser(_ browser: MCBrowserViewController, didConnectPeer peerID: MCPeerID, toSession session: MCSession) {
    dismiss(animated: true)
    print("Browser connected to \(peerID.displayName)")
    // Do NOT create a new MCSession here — use your existing mcSession instance
}

5. Debug with Detailed Logs #

Add logs to confirm the state of peers right before sending:

for peer in mcSession.connectedPeers {
    print("Peer: \(peer.displayName) | State: \(mcSession.state(for: peer))")
}

This will tell you if connectedPeers includes peers that are still in .connecting state, which is the most likely cause of your error.

内容的提问来源于stack exchange，提问作者JS__2008