iOS开发之联网状态检测

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    //不能写在viewDidLoad网络的情况发生变化的时候要提醒
    //判断能否连接到某一个主机(一般使用百度，他的服务器基本不会断)
     self.reach = [Reachability reachabilityWithHostName:@"baidu.com"];
    
    //添加一个通知
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(abilityChanged) name:kReachabilityChangedNotification object:nil];
    [self.reach startNotifier];
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context {
    NSLog(@"%@",change);
}


- (void)abilityChanged {
    //状态
    switch (self.reach.currentReachabilityStatus) {
        case NotReachable:
        {
            [self showMessage:@"小伙子没有连接哦"];
        }
            break;
        case ReachableViaWiFi:
        {
            [self showMessage:@"小伙子有WIFI咯"];
            NSLog(@"不用花钱");
        }
            break;
        case ReachableViaWWAN:
        {
　　　　　　　[self showMessage:@"当前网络状态为2G/3G/4G"];
            NSLog(@"要流量");
        }
            break;
        default:
        {
            NSLog(@"不太清楚");
        }
            break;
    }
}

- (void)showMessage:(NSString *)title {
    UIAlertController *alertCtr = [UIAlertController alertControllerWithTitle:title message:nil preferredStyle:UIAlertControllerStyleAlert];
    [self presentViewController:alertCtr animated:YES completion:nil];
}

- (void)dealloc {
    //停止监听
    [self.reach stopNotifier];
    //移除监听
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}