我正在尝试确定在使用 Network.framework 时 UDP 客户端何时停止向服务器发送数据包
我已经构建了一个小示例,该示例演示了服务器无法将状态更改.cancelled
为客户端连接被取消时的状态。
示例客户端:
import Foundation
import Network
func sendMessage(on connection: NWConnection) {
connection.send(content: "hello".data(using: .utf8), completion: .contentProcessed({error in
if let error = error {
print("error while sending hello: \(error)")
return
}
connection.receiveMessage {data, context, isComplete, error in
if let error = error {
print("error while receiving reply: \(error)")
return
}
connection.cancel()
}
}))
}
var connection: NWConnection = {
let connection = NWConnection(
to: .service(
name: "Hello",
type: "_test._udp",
domain: "local",
interface: nil
),
using: .udp
)
connection.stateUpdateHandler = {newState in
switch newState {
case .ready:
sendMessage(on: connection)
case .failed(let error):
print("client failed with error: \(error)")
case .cancelled:
print("Cancelled connection")
default:
break
}
}
return connection
}()
connection.start(queue: DispatchQueue(label: "test"))
RunLoop.main.run()
示例服务器:
import Foundation
import Network
func receive(on connection: NWConnection) {
connection.receiveMessage { (data, context, isComplete, error) in
if let error = error {
print(error)
return
}
connection.send(content: "world".data(using: .utf8), completion: .contentProcessed({error in
if let error = error {
print("error while sending data: \(error)")
return
}
}))
receive(on: connection)
}
}
var listener: NWListener = {
let listener = try! NWListener(using: .udp)
listener.service = NWListener.Service(name: "Hello", type: "_test._udp", domain: nil, txtRecord: nil)
listener.newConnectionHandler = {newConnection in
newConnection.stateUpdateHandler = {newState in
switch newState {
case .ready:
receive(on: newConnection)
case .failed(let error):
print("client failed with error: \(error)")
case .cancelled:
print("Cancelled connection")
default:
break
}
}
newConnection.start(queue: DispatchQueue(label: "new client"))
}
return listener
}()
listener.start(queue: DispatchQueue(label: "test"))
RunLoop.main.run()
在服务器运行的同时运行客户端时,客户端发送和接收一个数据包,然后被取消。客户端打印Connection cancelled
。但是,服务器上 NWConnection 的状态不会改变,connection.receiveMessage
当没有数据从客户端读取时,会静默失败。
我希望服务器连接的状态会改变或receiveMessage
调用其完成处理程序,尽管没有数据存在(data
毕竟Data?
)
因此,我不确定在 Network.framework 上使用 UDP 服务器时如何检测客户端何时停止发送数据包。我应该如何检测“断开连接”的客户端?