iOS网络检测Reachability 使用 Demo，可检测2、3、4G

你可以在Github下载这个Demo https://github.com/JanzTam/Reachability_Demo

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;
    }
}