iPhone判断是否接入网络

  在这里介绍一种较为简单的判断是否连接网络的方法，首先要引入Reachability.h和.m文件，没有这两个文件的话，google之。然后在***AppDelegate.h中声明如下：

	NetworkStatus remoteHostStatus;
	NetworkStatus internetConnectionStatus;
	NetworkStatus localWiFiConnectionStatus;

...

//Network
@property NetworkStatus remoteHostStatus;
@property NetworkStatus internetConnectionStatus;
@property NetworkStatus localWiFiConnectionStatus;
- (void) registerNetworkChecking;
- (void) updateNetworkStatus;

然后在.m中实现：

- (void) registerNetworkChecking
{
	[[Reachability sharedReachability] setHostName:@"www.baidu.com"];
	[[NSNotificationCenter defaultCenter] addObserver:self
											 selector:@selector(reachabilityChanged:)
												 name:@"kNetworkReachabilityChangedNotification"
											   object:nil];
	//[self updateNetworkStatus];
	
}
#pragma mark NetworkStatus Notification
- (void)reachabilityChanged:(NSNotification *)note
{
	//////NSLog(@"reachabilityChanged");
    [self updateNetworkStatus];
}

- (void)updateNetworkStatus
{
	// Query the SystemConfiguration framework for the state of the device's network connections.
	self.remoteHostStatus           = [[Reachability sharedReachability] remoteHostStatus];
	self.internetConnectionStatus	= [[Reachability sharedReachability] internetConnectionStatus];
	self.localWiFiConnectionStatus	= [[Reachability sharedReachability] localWiFiConnectionStatus];	
}

在需要判断的地方用：

	***AppDelegate *appDelegate = (***AppDelegate *)[[UIApplication sharedApplication] delegate];
	[appDelegate registerNetworkChecking];	
	if (appDelegate.remoteHostStatus == NotReachable)
	{
	      //未联网
	}
	else
	{
	      //联网
	}