1.创建网络监听者管理者对象

AFNetworkReachabilityManager *manager = [AFNetworkReachabilityManager sharedManager];

2.设置监听

1)网络状态

//显然是枚举值
typedef NS_ENUM(NSInteger, AFNetworkReachabilityStatus) {
    AFNetworkReachabilityStatusUnknown          = -1,//未识别的网络
    AFNetworkReachabilityStatusNotReachable     = 0,//不可达的网络
    AFNetworkReachabilityStatusReachableViaWWAN = 1,//2G,3G,4G...
    AFNetworkReachabilityStatusReachableViaWiFi = 2,//wifi网络
    }

2)设置网络监听

[manager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
    switch (status) {
        case AFNetworkReachabilityStatusUnknown:
            NSLog(@"未识别的网络");
            break;

        case AFNetworkReachabilityStatusNotReachable:
            NSLog(@"不可达的网络(未连接)");
            break;

        case AFNetworkReachabilityStatusReachableViaWWAN:
            NSLog(@"2G,3G,4G...的网络");
            break;

        case AFNetworkReachabilityStatusReachableViaWiFi:
            NSLog(@"wifi的网络");
            break;
        default:
            break;
    }
}];

3.开始监听

[manager startMonitoring];