首先，引入系统的Reachability类，不知道怎么引入的话，在Xcode，按下shift+command+0，搜索Reachability，看到图中所选的工程下载即可。

Reachability.png

并导入相关.h文件

#import<CoreTelephony/CTTelephonyNetworkInfo.h>

引入后，Reachability.h文件里面修改NetworkStatus的枚举，

typedef enum : NSInteger {

    NotReachable = 0,

    ReachableViaWiFi,

    ReachableViaWWAN,

    kReachableVia2G,

    kReachableVia3G,

    kReachableVia4G

} NetworkStatus;

在修改下Reachability.m文件
找到

- (NetworkStatus)networkStatusForFlags:(SCNetworkReachabilityFlags)flags

修改下面的代码

if ((flags & kSCNetworkReachabilityFlagsIsWWAN) == kSCNetworkReachabilityFlagsIsWWAN)

    {

if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0)

        {

            CTTelephonyNetworkInfo * info = [[CTTelephonyNetworkInfo alloc] init];

            NSString *currentRadioAccessTechnology = info.currentRadioAccessTechnology;

            if (currentRadioAccessTechnology)

            {

                if ([currentRadioAccessTechnology isEqualToString:CTRadioAccessTechnologyLTE])

                {

                    returnValue =  kReachableVia4G;

                }

                else if ([currentRadioAccessTechnology isEqualToString:CTRadioAccessTechnologyEdge] || [currentRadioAccessTechnology isEqualToString:CTRadioAccessTechnologyGPRS])

                {

                    returnValue =  kReachableVia2G;

                }

                else

                {

                    returnValue =  kReachableVia3G;

                }

                return returnValue;

            }

        }

        if ((flags & kSCNetworkReachabilityFlagsTransientConnection) == kSCNetworkReachabilityFlagsTransientConnection)

        {

            if((flags & kSCNetworkReachabilityFlagsConnectionRequired) == kSCNetworkReachabilityFlagsConnectionRequired)

            {

                returnValue =  kReachableVia2G;

                return returnValue;

            }

            returnValue =  kReachableVia3G;

            return returnValue;

        }

        returnValue = ReachableViaWWAN;

    }

如何使用？

在AppDelegate里加入

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

{

    //设置状态栏

    [[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleDefault];

    // 监测网络情况

    [[NSNotificationCenter defaultCenter] addObserver:self

                                             selector:@selector(reachabilityChanged:)

                                                 name: kReachabilityChangedNotification

                                               object: nil];

    hostReach = [Reachability reachabilityWithHostName:@"www.baidu.com"];

    [hostReach startNotifier];

}

- (void)reachabilityChanged:(NSNotification *)note

{

    Reachability* curReach = [note object];

    NSParameterAssert([curReach isKindOfClass: [Reachability class]]);

    NetworkStatus status = [curReach currentReachabilityStatus];

    switch (status)

    {

        case NotReachable:

            break;

        case ReachableViaWiFi:

        case ReachableViaWWAN:

            break;

        case kReachableVia2G:

            break;

        case kReachableVia3G:

            break;

        case kReachableVia4G:

            break;

    }

}