我喜欢把事情简单化。我的做法是:

//Class.h
#import "Reachability.h"
#import <SystemConfiguration/SystemConfiguration.h>

- (BOOL)connected;

//Class.m
- (BOOL)connected
{
    Reachability *reachability = [Reachability reachabilityForInternetConnection];
    NetworkStatus networkStatus = [reachability currentReachabilityStatus];
    return networkStatus != NotReachable;
}

然后，每当我想要查看是否有连接时，我就使用这个:

if (![self connected]) {
    // Not connected
} else {
    // Connected. Do some Internet stuff
}

这个方法不会等待网络状态的改变来执行操作。它只在您要求时测试状态。

//
//  Connectivity.swift
// 
//
//  Created by Kausik Jati on 17/07/20.
// 
//

import Foundation
import Network

enum ConnectionState: String {
    case notConnected = "Internet connection not avalable"
    case connected = "Internet connection avalable"
    case slowConnection = "Internet connection poor"
}
protocol ConnectivityDelegate: class {
    func checkInternetConnection(_ state: ConnectionState, isLowDataMode: Bool)
}
class Connectivity: NSObject {
    private let monitor = NWPathMonitor()
    weak var delegate: ConnectivityDelegate? = nil
    private let queue = DispatchQueue.global(qos: .background)
    private var isLowDataMode = false
    static let instance = Connectivity()
private override init() {
    super.init()
    monitor.start(queue: queue)
    startMonitorNetwork()
}
private func startMonitorNetwork() {
    monitor.pathUpdateHandler = { path in
        if #available(iOS 13.0, *) {
            self.isLowDataMode = path.isConstrained
        } else {
            // Fallback on earlier versions
            self.isLowDataMode = false
        }
        
        if path.status == .requiresConnection {
            print("requiresConnection")
                self.delegate?.checkInternetConnection(.slowConnection, isLowDataMode: self.isLowDataMode)
        } else if path.status == .satisfied {
            print("satisfied")
                 self.delegate?.checkInternetConnection(.connected, isLowDataMode: self.isLowDataMode)
        } else if path.status == .unsatisfied {
            print("unsatisfied")
                self.delegate?.checkInternetConnection(.notConnected, isLowDataMode: self.isLowDataMode)
            }
        }
    
    }
    func stopMonitorNetwork() {
        monitor.cancel()
    }
}

使用Apple的Reachability代码，我创建了一个函数，可以正确地检查这一点，而无需包含任何类。

在你的项目中包含SystemConfiguration.framework。

进行一些导入:

#import <sys/socket.h>
#import <netinet/in.h>
#import <SystemConfiguration/SystemConfiguration.h>

现在只需调用这个函数:

/*
Connectivity testing code pulled from Apple's Reachability Example: https://developer.apple.com/library/content/samplecode/Reachability
 */
+(BOOL)hasConnectivity {
    struct sockaddr_in zeroAddress;
    bzero(&zeroAddress, sizeof(zeroAddress));
    zeroAddress.sin_len = sizeof(zeroAddress);
    zeroAddress.sin_family = AF_INET;

    SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, (const struct sockaddr*)&zeroAddress);
    if (reachability != NULL) {
        //NetworkStatus retVal = NotReachable;
        SCNetworkReachabilityFlags flags;
        if (SCNetworkReachabilityGetFlags(reachability, &flags)) {
            if ((flags & kSCNetworkReachabilityFlagsReachable) == 0)
            {
                // If target host is not reachable
                return NO;
            }

            if ((flags & kSCNetworkReachabilityFlagsConnectionRequired) == 0)
            {
                // If target host is reachable and no connection is required
                //  then we'll assume (for now) that your on Wi-Fi
                return YES;
            }


            if ((((flags & kSCNetworkReachabilityFlagsConnectionOnDemand ) != 0) ||
                 (flags & kSCNetworkReachabilityFlagsConnectionOnTraffic) != 0))
            {
                // ... and the connection is on-demand (or on-traffic) if the
                //     calling application is using the CFSocketStream or higher APIs.

                if ((flags & kSCNetworkReachabilityFlagsInterventionRequired) == 0)
                {
                    // ... and no [user] intervention is needed
                    return YES;
                }
            }

            if ((flags & kSCNetworkReachabilityFlagsIsWWAN) == kSCNetworkReachabilityFlagsIsWWAN)
            {
                // ... but WWAN connections are OK if the calling application
                //     is using the CFNetwork (CFSocketStream?) APIs.
                return YES;
            }
        }
    }

    return NO;
}

这是为你测试的iOS 5。

创建一个AFNetworkReachabilityManager对象，并使用以下代码跟踪网络连通性

self.reachabilityManager = [AFNetworkReachabilityManager managerForDomain:@"yourDomain"];
[self.reachabilityManager startMonitoring];
[self.reachabilityManager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
        switch (status) {
            case AFNetworkReachabilityStatusReachableViaWWAN:
            case AFNetworkReachabilityStatusReachableViaWiFi:
                break;
            case AFNetworkReachabilityStatusNotReachable:
                break;
            default:
                break;
        }
    }];

苹果提供了一个示例应用程序，它正是这样做的:

可达性

自己做这件事非常简单。下面的方法是可行的。只是要确保不允许将主机名协议(如HTTP、HTTPS等)与名称一起传入。

-(BOOL)hasInternetConnection:(NSString*)urlAddress
{
    SCNetworkReachabilityRef ref = SCNetworkReachabilityCreateWithName(kCFAllocatorDefault, [urlAddress UTF8String]);
    SCNetworkReachabilityFlags flags;
    if (!SCNetworkReachabilityGetFlags(ref, &flags))
    {
        return NO;
    }
    return flags & kSCNetworkReachabilityFlagsReachable;
}

这是快速、简单和无痛的。