如何在 Swift 中使用 SCNetworkReacability

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最佳答案

(This answer was extended repeatedly due to changes in the Swift language, which made it a bit confusing. I have now rewritten it and removed everything which refers to Swift 1.x. The older code can be found in the edit history if somebody needs it.)

This is how you would do it in Swift 2.0 (Xcode 7):

import SystemConfiguration


func connectedToNetwork() -> Bool {


var zeroAddress = sockaddr_in()
zeroAddress.sin_len = UInt8(sizeofValue(zeroAddress))
zeroAddress.sin_family = sa_family_t(AF_INET)


guard let defaultRouteReachability = withUnsafePointer(&zeroAddress, {
SCNetworkReachabilityCreateWithAddress(nil, UnsafePointer($0))
}) else {
return false
}


var flags : SCNetworkReachabilityFlags = []
if !SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) {
return false
}


let isReachable = flags.contains(.Reachable)
let needsConnection = flags.contains(.ConnectionRequired)


return (isReachable && !needsConnection)
}

Explanations:

As of Swift 1.2 (Xcode 6.3), imported C structs have a default initializer in Swift, which initializes all of the struct's fields to zero, so the socket address structure can be initialized with
```
var zeroAddress = sockaddr_in()
```
sizeofValue() gives the size of this structure, this has to be converted to UInt8 for sin_len:
```
zeroAddress.sin_len = UInt8(sizeofValue(zeroAddress))
```
AF_INET is an Int32, this has to be converted to the correct type for sin_family:
```
zeroAddress.sin_family = sa_family_t(AF_INET)
```
withUnsafePointer(&zeroAddress) { ... } passes the address of the structure to the closure where it is used as argument for SCNetworkReachabilityCreateWithAddress(). The UnsafePointer($0) conversion is needed because that function expects a pointer to sockaddr, not sockaddr_in.
The value returned from withUnsafePointer() is the return value from SCNetworkReachabilityCreateWithAddress() and that has the type SCNetworkReachability?, i.e. it is an optional. The guard let statement (a new feature in Swift 2.0) assigns the unwrapped value to the defaultRouteReachability variable if it is not nil. Otherwise the else block is executed and the function returns.
As of Swift 2, SCNetworkReachabilityCreateWithAddress() returns a managed object. You don't have to release it explicitly.
As of Swift 2, SCNetworkReachabilityFlags conforms to OptionSetType which has a set-like interface. You create an empty flags variable with
```
var flags : SCNetworkReachabilityFlags = []
```
and check for flags with
```
let isReachable = flags.contains(.Reachable)
let needsConnection = flags.contains(.ConnectionRequired)
```
The second parameter of SCNetworkReachabilityGetFlags has the type UnsafeMutablePointer<SCNetworkReachabilityFlags>, which means that you have to pass the address of the flags variable.

Note also that registering a notifier callback is possible as of Swift 2, compare Working with C APIs from Swift and Swift 2 - UnsafeMutablePointer<Void> to object.

Update for Swift 3/4:

Unsafe pointers cannot be simply be converted to a pointer of a different type anymore (see - SE-0107 UnsafeRawPointer API). Here the updated code:

import SystemConfiguration


func connectedToNetwork() -> Bool {


var zeroAddress = sockaddr_in()
zeroAddress.sin_len = UInt8(MemoryLayout<sockaddr_in>.size)
zeroAddress.sin_family = sa_family_t(AF_INET)


guard let defaultRouteReachability = withUnsafePointer(to: &zeroAddress, {
$0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
SCNetworkReachabilityCreateWithAddress(nil, $0)
}
}) else {
return false
}


var flags: SCNetworkReachabilityFlags = []
if !SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags) {
return false
}


let isReachable = flags.contains(.reachable)
let needsConnection = flags.contains(.connectionRequired)


return (isReachable && !needsConnection)
}

小开

The best solution is to use ReachabilitySwift class, written in Swift 2, and uses SCNetworkReachabilityRef.

Simple and easy:

let reachability = Reachability.reachabilityForInternetConnection()


reachability?.whenReachable = { reachability in
// keep in mind this is called on a background thread
// and if you are updating the UI it needs to happen
// on the main thread, like this:
dispatch_async(dispatch_get_main_queue()) {
if reachability.isReachableViaWiFi() {
print("Reachable via WiFi")
} else {
print("Reachable via Cellular")
}
}
}
reachability?.whenUnreachable = { reachability in
// keep in mind this is called on a background thread
// and if you are updating the UI it needs to happen
// on the main thread, like this:
dispatch_async(dispatch_get_main_queue()) {
print("Not reachable")
}
}


reachability?.startNotifier()

Working like a charm.

Enjoy

小开

This has nothing to do with Swift, but the best solution is to NOT use Reachability to determine whether the network is online. Just make your connection and handle errors if it fails. Making a connection can at times fire up the dormant offline radios.

The one valid use of Reachability is to use it to notify you when a network transitions from offline to online. At that point you should retry failed connections.

小开

Swift 3, IPv4, IPv6

Based on the Martin R's answer:

import SystemConfiguration


func isConnectedToNetwork() -> Bool {
guard let flags = getFlags() else { return false }
let isReachable = flags.contains(.reachable)
let needsConnection = flags.contains(.connectionRequired)
return (isReachable && !needsConnection)
}


func getFlags() -> SCNetworkReachabilityFlags? {
guard let reachability = ipv4Reachability() ?? ipv6Reachability() else {
return nil
}
var flags = SCNetworkReachabilityFlags()
if !SCNetworkReachabilityGetFlags(reachability, &flags) {
return nil
}
return flags
}


func ipv6Reachability() -> SCNetworkReachability? {
var zeroAddress = sockaddr_in6()
zeroAddress.sin6_len = UInt8(MemoryLayout<sockaddr_in>.size)
zeroAddress.sin6_family = sa_family_t(AF_INET6)


return withUnsafePointer(to: &zeroAddress, {
$0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
SCNetworkReachabilityCreateWithAddress(nil, $0)
}
})
}


func ipv4Reachability() -> SCNetworkReachability? {
var zeroAddress = sockaddr_in()
zeroAddress.sin_len = UInt8(MemoryLayout<sockaddr_in>.size)
zeroAddress.sin_family = sa_family_t(AF_INET)


return withUnsafePointer(to: &zeroAddress, {
$0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
SCNetworkReachabilityCreateWithAddress(nil, $0)
}
})
}

小开

updated juanjo's answer to create singleton instance

import Foundation
import SystemConfiguration


final class Reachability {


private init () {}
class var shared: Reachability {
struct Static {
static let instance: Reachability = Reachability()
}
return Static.instance
}


func isConnectedToNetwork() -> Bool {
guard let flags = getFlags() else { return false }
let isReachable = flags.contains(.reachable)
let needsConnection = flags.contains(.connectionRequired)
return (isReachable && !needsConnection)
}


private func getFlags() -> SCNetworkReachabilityFlags? {
guard let reachability = ipv4Reachability() ?? ipv6Reachability() else {
return nil
}
var flags = SCNetworkReachabilityFlags()
if !SCNetworkReachabilityGetFlags(reachability, &flags) {
return nil
}
return flags
}


private func ipv6Reachability() -> SCNetworkReachability? {
var zeroAddress = sockaddr_in6()
zeroAddress.sin6_len = UInt8(MemoryLayout<sockaddr_in>.size)
zeroAddress.sin6_family = sa_family_t(AF_INET6)


return withUnsafePointer(to: &zeroAddress, {
$0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
SCNetworkReachabilityCreateWithAddress(nil, $0)
}
})
}
private func ipv4Reachability() -> SCNetworkReachability? {
var zeroAddress = sockaddr_in()
zeroAddress.sin_len = UInt8(MemoryLayout<sockaddr_in>.size)
zeroAddress.sin_family = sa_family_t(AF_INET)


return withUnsafePointer(to: &zeroAddress, {
$0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
SCNetworkReachabilityCreateWithAddress(nil, $0)
}
})
}
}

Usage

if Reachability.shared.isConnectedToNetwork(){


}

小开

This is in Swift 4.0

I am using this framework https://github.com/ashleymills/Reachability.swift
And Install Pod ..
In AppDelegate

var window: UIWindow?
var reachability = InternetReachability()!
var reachabilityViewController : UIViewController? = nil


func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.


reachabilityChecking()
return true
}


extension AppDelegate {


func reachabilityChecking() {
reachability.whenReachable = { reachability in
DispatchQueue.main.async {
print("Internet is OK!")
if reachability.connection != .none && self.reachabilityViewController != nil {


}
}
}
reachability.whenUnreachable = { _ in
DispatchQueue.main.async {
print("Internet connection FAILED!")
let storyboard = UIStoryboard(name: "Reachability", bundle: Bundle.main)
self.reachabilityViewController = storyboard.instantiateViewController(withIdentifier: "ReachabilityViewController")
let rootVC = self.window?.rootViewController
rootVC?.present(self.reachabilityViewController!, animated: true, completion: nil)
}
}
do {
try reachability.startNotifier()
} catch {
print("Could not start notifier")
}
}
}

The reachabilityViewController screen will appear if internet is not there

小开

Swift 5, Using NWPathMonitor

import Network


func configureNetworkMonitor(){
let monitor = NWPathMonitor()
        

monitor.pathUpdateHandler = { path in
            

if path.status != .satisfied {
print("not connected")
}
else if path.usesInterfaceType(.cellular) {
print("Cellular")
}
else if path.usesInterfaceType(.wifi) {
print("WIFI")
}
else if path.usesInterfaceType(.wiredEthernet) {
print("Ethernet")
}
else if path.usesInterfaceType(.other){
print("Other")
}else if path.usesInterfaceType(.loopback){
print("Loop Back")
}
}
        

monitor.start(queue: DispatchQueue.global(qos: .background))
}

小开

A SwiftUI take on Mithra Sigam's solution above:

import SwiftUI
import Network


class NetworkReachabilityManager: ObservableObject {
@Published var networkPathStatus: NWPath.Status
@Published var availableInterfaces: [NWInterface]
    

let monitor = NWPathMonitor()
    

init() {
monitor.start(queue: DispatchQueue.global(qos: .background))
        

let currentPath = monitor.currentPath
        

networkPathStatus = currentPath.status
availableInterfaces = currentPath.availableInterfaces
        

monitor.pathUpdateHandler = { [self] networkPath in
DispatchQueue.main.async {
networkPathStatus = networkPath.status
availableInterfaces = networkPath.availableInterfaces
}
}
}
    

deinit {
monitor.cancel()
}
}