iOS 检测网络状态的两种方法

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{//开启网络状况的监听//来订阅实时的网络状态变化通知。导入Reachability.h头文件，然后注册一个对象来订阅网络状态变化的信息，网络状态变化的信息名称为kReachabilityChanged-Notification[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:kReachabilityChangedNotification object:nil];//通过检查某个主机能否访问来判断当前网络是否可用：self.hostReach = [Reachability reachabilityWithHostName:@"www.baidu.com"] ;//开始监听，会启动一个run loop[self.hostReach startNotifier];}-(void)reachabilityChanged:(NSNotification *)note{Reachability *currReach = [note object];NSParameterAssert([currReach isKindOfClass:[Reachability class]]);//对连接改变做出响应处理动作NetworkStatus status = [currReach currentReachabilityStatus];//如果没有连接到网络就弹出提醒实况self.isReachable = YES;if(status == NotReachable){UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"网络连接异常" message:nil delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil];[alert show];[alert release];self.isReachable = NO;return;}if (status==kReachableViaWiFi||status==kReachableViaWWAN) {UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"网络连接信息" message:@"网络连接正常" delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil];// [alert show];[alert release];self.isReachable = YES;}}

-(void)viewWillAppear:(BOOL)animated{[super viewWillAppear:YES];AppDelegate *appDlg = (AppDelegate *)[[UIApplication sharedApplication] delegate];if(appDlg.isReachable){NSLog(@"网络已连接");//执行网络正常时的代码}else{NSLog(@"网络连接异常");//执行网络异常时的代码UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"网络连接异常" message:nil delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil];[alert show];[alert release];}}

-(void)afn{//1.创建网络状态监测管理者AFNetworkReachabilityManager *manger = [AFNetworkReachabilityManager sharedManager];//开启监听，记得开启，不然不走block[manger startMonitoring];//2.监听改变[manger setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {/*AFNetworkReachabilityStatusUnknown = -1,AFNetworkReachabilityStatusNotReachable = 0,AFNetworkReachabilityStatusReachableViaWWAN = 1,AFNetworkReachabilityStatusReachableViaWiFi = 2,*/switch (status) {case AFNetworkReachabilityStatusUnknown:NSLog(@"未知");break;case AFNetworkReachabilityStatusNotReachable:NSLog(@"没有网络");break;case AFNetworkReachabilityStatusReachableViaWWAN:NSLog(@"3G|4G");break;case AFNetworkReachabilityStatusReachableViaWiFi:NSLog(@"WiFi");break;default:break;}}];}