A bidirectional data connection between a local endpoint and a remote endpoint.
SDKs
- iOS 12.0+
- macOS 10.14+
- Mac Catalyst 13.0+
- tvOS 12.0+
- watchOS 5.0+
- Xcode 10.0+
Framework
- Network
Declaration
final class NWConnection
Class
NWConnection
Topics
Creating Connections
init(host: NWEndpointInitializes a new connection to a host and port.
init(to: NWEndpoint, using: NWParameters)Initializes a new connection to a remote endpoint.
func start(queue: DispatchStarts establishing a connection, and sets the queue on which to deliver all connection events.
func restart()Restarts a connection that is in the waiting state.
Handling State Updates
var state: NWConnectionThe current state of the connection.
enum NWConnectionStates indicating whether a connection can be used to send and receive data.
var stateA handler that receives connection state updates.
Sending and Receiving Data
enum NWConnectionA completion handler that indicates when the connection has finished processing sent content.
func receive(minimumSchedules a single receive completion handler, with a range indicating how many bytes the handler can receive at one time.
func receiveSchedules a single receive completion handler for a complete message, as opposed to a range of bytes.
func batch(() -> Void)Defines a block in which calls to send and receive are processed as a batch to improve performance.
class NWConnectionAn object that represents a message to send or receive, containing protocol metadata and send properties.
var maximumThe maximum size of a datagram message that can be sent on a connection.
Canceling Connections
func cancel()Cancels the connection and gracefully disconnects any established network protocols.
func forceCancels the connection and immediately disconnects any established network protocols.
func cancelCauses the current endpoint to be rejected, allowing the connection to try another resolved address.
Handling Path Updates
var currentThe network path the connection is using.
var pathA handler that receives network path updates.
var viabilityA handler that receives updates when data can be sent and received.
var betterA handler that receives updates when an alternative network path is preferred over the current path.
Collecting Connection Metrics
Collecting Network Connection Metrics
Use reports to understand how DNS and protocol handshakes impact connection establishment.
func requestRequests a copy of the connection's establishment report once the connection is in the ready state.
struct NWConnectionA report that provides metrics about how a connection was established.
func startBegins a new data transfer report, which can later be collected.
class NWConnectionAn outstanding data transfer report that has yet to be collected.
struct NWConnectionA report that provides metrics about data being sent and received on a connection.
Inspecting Connections
func metadata(definition: NWProtocolRetrieves the connection-wide metadata for a specific protocol.
class NWProtocolThe abstract superclass for specifying metadata about a network protocol.
let endpoint: NWEndpointThe remote endpoint with which the connection was initialized.
let parameters: NWParametersThe parameters with which the connection was initialized.
var queue: DispatchThe queue on which connection events are delivered.
var debugThe description of the connection.
Relationships
Conforms To
See Also
Connections and Listeners
class NWListenerAn object you use to listen for incoming network connections.
class NWBrowserAn object you use to browse for available network services.
class NWEthernetAn object you use to send and receive custom Ethernet frames.