网络状态监听

一、在 AppDelegate.m 中创建监听单例，并监听发起通知

AFNetworkReachabilityManager *manager = [AFNetworkReachabilityManager sharedManager];
    [manager setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
        [[NSNotificationCenter defaultCenter] postNotificationName:@"AFNetworkReachabilityStatusNotification" object:nil userInfo:@{@"status" : @(status)}];
    }];
    [manager startMonitoring];

二、在任意地方接收状态通知，此非block通知，iOS9后无需移除监听，不会强引用

- (void)viewDidLoad {
    [super viewDidLoad];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(receiveAFNetworkingReachabilityStatusNotification:) name:@"AFNetworkReachabilityStatusNotification" object:nil];
}

- (void)receiveAFNetworkingReachabilityStatusNotification:(NSNotification *)notification {
    NSDictionary *userInfo = notification.userInfo;
    NSInteger status = [[userInfo valueForKey:@"status"] integerValue];
    switch (status) {
            // 未知网络
        case AFNetworkReachabilityStatusUnknown:
            // 无网络
        case AFNetworkReachabilityStatusNotReachable:
        {
            NSLog(@">>>>>>>>无网络aa");
            
            break;
        }
            // 蜂窝数据
        case AFNetworkReachabilityStatusReachableViaWWAN:
            // wifi
        case AFNetworkReachabilityStatusReachableViaWiFi:
        {
            NSLog(@">>>>>>>>Wifiaa");
            
            break;
        }
    }
}