Swift SocketIO客户端无法连接：模拟器环境下的问题求助

问题 #

通过Swift Package Manager安装swift-socketio-client后，使用以下代码尝试建立Socket连接（测试环境为模拟器）：

let manager = SocketManager(socketURL: URL(string: "http://127.0.0.1:3000")!, config: [.log(true)])
let defaultNamespaceSocket = manager.defaultSocket
let socket = manager.socket(forNamespace: "/message")

socket.on(clientEvent: .connect) {data, ack in
    print("socket connected")
}

socket.connect()

API未记录新连接，connect回调也未执行。Postman验证URL有效，日志信息如下：

LOG SocketIOClient{/message}: Adding handler for event: connect
LOG SocketIOClient{/message}: Handling event: statusChange with data: [connecting, 2]
LOG SocketIOClient{/message}: Joining namespace /message
LOG SocketManager: Tried connecting socket when engine isn't open. Connecting
LOG SocketManager: Adding engine
LOG SocketManager: Manager is being released
LOG SocketIOClient{/message}: Client is being released
LOG SocketEngine: Starting engine. Server: http://127.0.0.1:3000
LOG SocketEngine: Handshaking
LOG SocketIOClient{/}: Client is being released
LOG SocketEnginePolling: Doing polling GET http://127.0.0.1:3000/socket.io/?transport=polling&b64=1&EIO=4
LOG SocketEnginePolling: Got polling response
LOG SocketEnginePolling: Got poll message: 0{"sid":"tLgrfJ8T1cQKPms8AAAJ","upgrades":["websocket"],"pingInterval":25000,"pingTimeout":60000,"maxPayload":100000000}
LOG SocketEngine: Got message: 0{"sid":"tLgrfJ8T1cQKPms8AAAJ","upgrades":["websocket"],"pingInterval":25000,"pingTimeout":60000,"maxPayload":100000000}
LOG SocketEngine: Engine is being released
nw_connection_copy_connected_local_endpoint_block_invoke [C2] Client called nw_connection_copy_connected_local_endpoint on unconnected nw_connection
nw_connection_copy_connected_remote_endpoint_block_invoke [C2] Client called nw_connection_copy_connected_remote_endpoint on unconnected nw_connection

故障原因及解决方案 #

• 核心原因：Socket对象被提前释放
  从日志里的SocketManager: Manager is being released和SocketIOClient{/message}: Client is being released可以明确看出，manager和socket都是局部变量，代码执行完当前作用域后，ARC会立即回收这些对象，导致连接流程中途中断，自然无法触发connect回调。

• 解决方案：将Socket对象声明为类属性或全局变量
  把manager和socket提升到类的实例属性（比如ViewController的属性），或者声明为全局变量，确保它们在连接的整个生命周期内保持引用，不会被提前回收。修改示例如下：

  class ViewController: UIViewController {
      // 声明为类属性，保持引用
      private let socketManager = SocketManager(socketURL: URL(string: "http://127.0.0.1:3000")!, config: [.log(true)])
      private var messageSocket: SocketIOClient!
      
      override func viewDidLoad() {
          super.viewDidLoad()
          messageSocket = socketManager.socket(forNamespace: "/message")
          
          messageSocket.on(clientEvent: .connect) { data, ack in
              print("socket connected")
          }
          
          messageSocket.connect()
      }
  }
  

• 额外检查点
  确认服务器端已正确配置/message命名空间，允许客户端接入；同时确保模拟器和服务器在同一网络环境（本地127.0.0.1是没问题的，因为模拟器共享主机网络）。

内容的提问来源于stack exchange，提问作者Alms