这是我的版本。本质上，它没有带来任何新东西。我把它绑定到UIDevice。

import UIKit
import SystemConfiguration

extension UIDevice {

    open class var isConnectedToNetwork: Bool {
        get {
            var zeroAddress = sockaddr_in()
            zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
            zeroAddress.sin_family = sa_family_t(AF_INET)

            guard
                let defaultRouteReachability: SCNetworkReachability = withUnsafePointer(to: &zeroAddress, {
                    $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {
                        SCNetworkReachabilityCreateWithAddress(nil, $0)
                    }
                }),
                var flags: SCNetworkReachabilityFlags = SCNetworkReachabilityFlags() as SCNetworkReachabilityFlags?,
                SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags)
                else { return false }

            return flags.contains(.reachable) && !flags.contains(.connectionRequired)
        }
    }

}

print("Network status availability: " + ( UIDevice.isConnectedToNetwork ? "true" : "false" ))

这是与接受的答案相同的代码，但我发现在某些情况下使用闭包更有用

import SystemConfiguration

public class Reachability {

    class func isConnectedToNetwork(isConnected : (Bool) -> ()) {

        var zeroAddress = sockaddr_in(sin_len: 0, sin_family: 0, sin_port: 0, sin_addr: in_addr(s_addr: 0), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
        zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
        zeroAddress.sin_family = sa_family_t(AF_INET)

        let defaultRouteReachability = withUnsafePointer(to: &zeroAddress) {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {zeroSockAddress in
                SCNetworkReachabilityCreateWithAddress(nil, zeroSockAddress)
            }
        }

        var flags: SCNetworkReachabilityFlags = SCNetworkReachabilityFlags(rawValue: 0)
        if SCNetworkReachabilityGetFlags(defaultRouteReachability!, &flags) == false {
            isConnected(false)
        }

        /* Only Working for WIFI
        let isReachable = flags == .reachable
        let needsConnection = flags == .connectionRequired

        return isReachable && !needsConnection
        */

        // Working for Cellular and WIFI
        let isReachable = (flags.rawValue & UInt32(kSCNetworkFlagsReachable)) != 0
        let needsConnection = (flags.rawValue & UInt32(kSCNetworkFlagsConnectionRequired)) != 0
        let ret = (isReachable && !needsConnection)

        isConnected(ret)
    }
}

下面是如何使用它:

Reachability.isConnectedToNetwork { (isConnected) in
    if isConnected {
        //We have internet connection | get data from server
    } else {
        //We don't have internet connection | load from database 
    }
}

在Swift-5+上使用这个

import Foundation
import UIKit
import SystemConfiguration

public class InternetConnectionManager {
    
    
    private init() {
        
    }
    
    public static func isConnectedToNetwork() -> Bool {
        
        var zeroAddress = sockaddr_in()
        zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
        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.rawValue & UInt32(kSCNetworkFlagsReachable)) != 0
        let needsConnection = (flags.rawValue & UInt32(kSCNetworkFlagsConnectionRequired)) != 0
        return (isReachable && !needsConnection)
    }
    
}

用法:

if InternetConnectionManager.isConnectedToNetwork(){
    print("Connected")
}else{
    print("Not Connected")
}

或者只是使用这个框架更多的实用程序:链接

这里是我的解决方案swift 2.3与库(reach .swift)

进入你的Podfile并添加:

pod 'ReachabilitySwift', '~> 2.4' // swift 2.3

然后进入您的终端:

pod install

然后创建一个新的文件ReachabilityManager并添加下面的代码:

import Foundation
import ReachabilitySwift

enum ReachabilityManagerType {
    case Wifi
    case Cellular
    case None
}

class ReachabilityManager {
    static let sharedInstance = ReachabilityManager()

    private var reachability: Reachability!
    private var reachabilityManagerType: ReachabilityManagerType = .None


    private init() {
        do {
            self.reachability = try Reachability.reachabilityForInternetConnection()
        } catch {
            print("Unable to create Reachability")
            return
        }

        NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(ReachabilityManager.reachabilityChanged(_:)),name: ReachabilityChangedNotification,object: self.reachability)
        do{
            try self.reachability.startNotifier()
        }catch{
            print("could not start reachability notifier")
        }
    }

    @objc private func reachabilityChanged(note: NSNotification) {

        let reachability = note.object as! Reachability

        if reachability.isReachable() {
            if reachability.isReachableViaWiFi() {
                self.reachabilityManagerType = .Wifi
            } else {
                self.reachabilityManagerType = .Cellular
            }
        } else {
            self.reachabilityManagerType = .None
        }
    }
}

extension ReachabilityManager {

    func isConnectedToNetwork() -> Bool {
        return reachabilityManagerType != .None
    }

}

如何使用:

进入你的AppDelegate.swift并添加下面的代码:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
     ReachabilityManager.sharedInstance
}

然后，当你想检查设备是否连接到互联网时，请:

if ReachabilityManager.sharedInstance.isConnectedToNetwork() {
   // Connected
} else {
  // Not connected
}

对于Swift 3, Swift 4(使用蜂窝和Wi-Fi):

import SystemConfiguration

public class Reachability {

    class func isConnectedToNetwork() -> Bool {

        var zeroAddress = sockaddr_in(sin_len: 0, sin_family: 0, sin_port: 0, sin_addr: in_addr(s_addr: 0), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
        zeroAddress.sin_len = UInt8(MemoryLayout.size(ofValue: zeroAddress))
        zeroAddress.sin_family = sa_family_t(AF_INET)

        let defaultRouteReachability = withUnsafePointer(to: &zeroAddress) {
            $0.withMemoryRebound(to: sockaddr.self, capacity: 1) {zeroSockAddress in
                SCNetworkReachabilityCreateWithAddress(nil, zeroSockAddress)
            }
        }

        var flags: SCNetworkReachabilityFlags = SCNetworkReachabilityFlags(rawValue: 0)
        if SCNetworkReachabilityGetFlags(defaultRouteReachability!, &flags) == false {
            return false
        }

        /* Only Working for WIFI
        let isReachable = flags == .reachable
        let needsConnection = flags == .connectionRequired

        return isReachable && !needsConnection
        */

        // Working for Cellular and WIFI
        let isReachable = (flags.rawValue & UInt32(kSCNetworkFlagsReachable)) != 0
        let needsConnection = (flags.rawValue & UInt32(kSCNetworkFlagsConnectionRequired)) != 0
        let ret = (isReachable && !needsConnection)

        return ret

    }
}

用法:

if Reachability.isConnectedToNetwork(){
    print("Internet Connection Available!")
}else{
    print("Internet Connection not Available!")
}

这是我自己发现的。

Xcode: 7.3.1, iOS 9.3.3

在我的项目中使用ashleymills/Reachability.swift作为Reachability.swift，我创建了以下函数:

func hasConnectivity() -> Bool {
    do {
        let reachability: Reachability = try Reachability.reachabilityForInternetConnection()
        let networkStatus: Int = reachability.currentReachabilityStatus.hashValue

        return (networkStatus != 0)
    }
    catch {
        // Handle error however you please
        return false
    }
}

只要在需要检查连接的地方调用hasConnectivity()即可。这适用于Wifi和蜂窝网络。

添加ashleyymills的reacbility .swift，这样人们就不必在不同的网站之间切换了:

Copyright (c) 2014, Ashley Mills
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/

// Reachability.swift version 2.2beta2

import SystemConfiguration
import Foundation

public enum ReachabilityError: ErrorType {
    case FailedToCreateWithAddress(sockaddr_in)
    case FailedToCreateWithHostname(String)
    case UnableToSetCallback
    case UnableToSetDispatchQueue
}

public let ReachabilityChangedNotification = "ReachabilityChangedNotification"

func callback(reachability:SCNetworkReachability, flags: SCNetworkReachabilityFlags, info: UnsafeMutablePointer<Void>) {
    let reachability = Unmanaged<Reachability>.fromOpaque(COpaquePointer(info)).takeUnretainedValue()

    dispatch_async(dispatch_get_main_queue()) {
        reachability.reachabilityChanged(flags)
    }
}


public class Reachability: NSObject {

    public typealias NetworkReachable = (Reachability) -> ()
    public typealias NetworkUnreachable = (Reachability) -> ()

    public enum NetworkStatus: CustomStringConvertible {

        case NotReachable, ReachableViaWiFi, ReachableViaWWAN

        public var description: String {
            switch self {
            case .ReachableViaWWAN:
                return "Cellular"
            case .ReachableViaWiFi:
                return "WiFi"
            case .NotReachable:
                return "No Connection"
            }
        }
    }

    // MARK: - *** Public properties ***
    public var whenReachable: NetworkReachable?
    public var whenUnreachable: NetworkUnreachable?
    public var reachableOnWWAN: Bool
    public var notificationCenter = NSNotificationCenter.defaultCenter()

    public var currentReachabilityStatus: NetworkStatus {
        if isReachable() {
            if isReachableViaWiFi() {
                return .ReachableViaWiFi
            }
            if isRunningOnDevice {
                return .ReachableViaWWAN
            }
        }
        return .NotReachable
    }

    public var currentReachabilityString: String {
        return "\(currentReachabilityStatus)"
    }

    private var previousFlags: SCNetworkReachabilityFlags?

    // MARK: - *** Initialisation methods ***

    required public init(reachabilityRef: SCNetworkReachability) {
        reachableOnWWAN = true
        self.reachabilityRef = reachabilityRef
    }

    public convenience init(hostname: String) throws {

        let nodename = (hostname as NSString).UTF8String
        guard let ref = SCNetworkReachabilityCreateWithName(nil, nodename) else { throw ReachabilityError.FailedToCreateWithHostname(hostname) }

        self.init(reachabilityRef: ref)
    }

    public class func reachabilityForInternetConnection() throws -> Reachability {

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

        guard let ref = withUnsafePointer(&zeroAddress, {
            SCNetworkReachabilityCreateWithAddress(nil, UnsafePointer($0))
        }) else { throw ReachabilityError.FailedToCreateWithAddress(zeroAddress) }

        return Reachability(reachabilityRef: ref)
    }

    public class func reachabilityForLocalWiFi() throws -> Reachability {

        var localWifiAddress: sockaddr_in = sockaddr_in(sin_len: __uint8_t(0), sin_family: sa_family_t(0), sin_port: in_port_t(0), sin_addr: in_addr(s_addr: 0), sin_zero: (0, 0, 0, 0, 0, 0, 0, 0))
        localWifiAddress.sin_len = UInt8(sizeofValue(localWifiAddress))
        localWifiAddress.sin_family = sa_family_t(AF_INET)

        // IN_LINKLOCALNETNUM is defined in <netinet/in.h> as 169.254.0.0
        let address: UInt32 = 0xA9FE0000
        localWifiAddress.sin_addr.s_addr = in_addr_t(address.bigEndian)

        guard let ref = withUnsafePointer(&localWifiAddress, {
            SCNetworkReachabilityCreateWithAddress(nil, UnsafePointer($0))
        }) else { throw ReachabilityError.FailedToCreateWithAddress(localWifiAddress) }

        return Reachability(reachabilityRef: ref)
    }

    // MARK: - *** Notifier methods ***
    public func startNotifier() throws {

        guard !notifierRunning else { return }

        var context = SCNetworkReachabilityContext(version: 0, info: nil, retain: nil, release: nil, copyDescription: nil)
        context.info = UnsafeMutablePointer(Unmanaged.passUnretained(self).toOpaque())

        if !SCNetworkReachabilitySetCallback(reachabilityRef!, callback, &context) {
            stopNotifier()
            throw ReachabilityError.UnableToSetCallback
        }

        if !SCNetworkReachabilitySetDispatchQueue(reachabilityRef!, reachabilitySerialQueue) {
            stopNotifier()
            throw ReachabilityError.UnableToSetDispatchQueue
        }

        // Perform an intial check
        dispatch_async(reachabilitySerialQueue) { () -> Void in
            let flags = self.reachabilityFlags
            self.reachabilityChanged(flags)
        }

        notifierRunning = true
    }

    public func stopNotifier() {
        defer { notifierRunning = false }
        guard let reachabilityRef = reachabilityRef else { return }

        SCNetworkReachabilitySetCallback(reachabilityRef, nil, nil)
        SCNetworkReachabilitySetDispatchQueue(reachabilityRef, nil)
    }

    // MARK: - *** Connection test methods ***
    public func isReachable() -> Bool {
        let flags = reachabilityFlags
        return isReachableWithFlags(flags)
    }

    public func isReachableViaWWAN() -> Bool {

        let flags = reachabilityFlags

        // Check we're not on the simulator, we're REACHABLE and check we're on WWAN
        return isRunningOnDevice && isReachable(flags) && isOnWWAN(flags)
    }

    public func isReachableViaWiFi() -> Bool {

        let flags = reachabilityFlags

        // Check we're reachable
        if !isReachable(flags) {
            return false
        }

        // Must be on WiFi if reachable but not on an iOS device (i.e. simulator)
        if !isRunningOnDevice {
            return true
        }

        // Check we're NOT on WWAN
        return !isOnWWAN(flags)
    }

    // MARK: - *** Private methods ***
    private var isRunningOnDevice: Bool = {
        #if (arch(i386) || arch(x86_64)) && os(iOS)
            return false
        #else
            return true
        #endif
    }()

    private var notifierRunning = false
    private var reachabilityRef: SCNetworkReachability?
    private let reachabilitySerialQueue = dispatch_queue_create("uk.co.ashleymills.reachability", DISPATCH_QUEUE_SERIAL)

    private func reachabilityChanged(flags: SCNetworkReachabilityFlags) {

        guard previousFlags != flags else { return }

        if isReachableWithFlags(flags) {
            if let block = whenReachable {
                block(self)
            }
        } else {
            if let block = whenUnreachable {
                block(self)
            }
        }

        notificationCenter.postNotificationName(ReachabilityChangedNotification, object:self)

        previousFlags = flags
    }

    private func isReachableWithFlags(flags: SCNetworkReachabilityFlags) -> Bool {

        if !isReachable(flags) {
            return false
        }

        if isConnectionRequiredOrTransient(flags) {
            return false
        }

        if isRunningOnDevice {
            if isOnWWAN(flags) && !reachableOnWWAN {
                // We don't want to connect when on 3G.
                return false
            }
        }

        return true
    }

    // WWAN may be available, but not active until a connection has been established.
    // WiFi may require a connection for VPN on Demand.
    private func isConnectionRequired() -> Bool {
        return connectionRequired()
    }

    private func connectionRequired() -> Bool {
        let flags = reachabilityFlags
        return isConnectionRequired(flags)
    }

    // Dynamic, on demand connection?
    private func isConnectionOnDemand() -> Bool {
        let flags = reachabilityFlags
        return isConnectionRequired(flags) && isConnectionOnTrafficOrDemand(flags)
    }

    // Is user intervention required?
    private func isInterventionRequired() -> Bool {
        let flags = reachabilityFlags
        return isConnectionRequired(flags) && isInterventionRequired(flags)
    }

    private func isOnWWAN(flags: SCNetworkReachabilityFlags) -> Bool {
        #if os(iOS)
            return flags.contains(.IsWWAN)
        #else
            return false
        #endif
    }
    private func isReachable(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags.contains(.Reachable)
    }
    private func isConnectionRequired(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags.contains(.ConnectionRequired)
    }
    private func isInterventionRequired(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags.contains(.InterventionRequired)
    }
    private func isConnectionOnTraffic(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags.contains(.ConnectionOnTraffic)
    }
    private func isConnectionOnDemand(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags.contains(.ConnectionOnDemand)
    }
    func isConnectionOnTrafficOrDemand(flags: SCNetworkReachabilityFlags) -> Bool {
        return !flags.intersect([.ConnectionOnTraffic, .ConnectionOnDemand]).isEmpty
    }
    private func isTransientConnection(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags.contains(.TransientConnection)
    }
    private func isLocalAddress(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags.contains(.IsLocalAddress)
    }
    private func isDirect(flags: SCNetworkReachabilityFlags) -> Bool {
        return flags.contains(.IsDirect)
    }
    private func isConnectionRequiredOrTransient(flags: SCNetworkReachabilityFlags) -> Bool {
        let testcase:SCNetworkReachabilityFlags = [.ConnectionRequired, .TransientConnection]
        return flags.intersect(testcase) == testcase
    }

    private var reachabilityFlags: SCNetworkReachabilityFlags {

        guard let reachabilityRef = reachabilityRef else { return SCNetworkReachabilityFlags() }

        var flags = SCNetworkReachabilityFlags()
        let gotFlags = withUnsafeMutablePointer(&flags) {
            SCNetworkReachabilityGetFlags(reachabilityRef, UnsafeMutablePointer($0))
        }

        if gotFlags {
            return flags
        } else {
            return SCNetworkReachabilityFlags()
        }
    }

    override public var description: String {

        var W: String
        if isRunningOnDevice {
            W = isOnWWAN(reachabilityFlags) ? "W" : "-"
        } else {
            W = "X"
        }
        let R = isReachable(reachabilityFlags) ? "R" : "-"
        let c = isConnectionRequired(reachabilityFlags) ? "c" : "-"
        let t = isTransientConnection(reachabilityFlags) ? "t" : "-"
        let i = isInterventionRequired(reachabilityFlags) ? "i" : "-"
        let C = isConnectionOnTraffic(reachabilityFlags) ? "C" : "-"
        let D = isConnectionOnDemand(reachabilityFlags) ? "D" : "-"
        let l = isLocalAddress(reachabilityFlags) ? "l" : "-"
        let d = isDirect(reachabilityFlags) ? "d" : "-"

        return "\(W)\(R) \(c)\(t)\(i)\(C)\(D)\(l)\(d)"
    }

    deinit {
        stopNotifier()

        reachabilityRef = nil
        whenReachable = nil
        whenUnreachable = nil
    }
}