iOS 에서 네트워크 상 태 를 감지 하 는 두 가지 방법

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{
//         
//              。  Reachability.h   ，                    ，            kReachabilityChanged-Notification
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:kReachabilityChangedNotification object:nil];
//                       ：
self.hostReach = [Reachability reachabilityWithHostName:@"www.baidu.com"] ;
//    ，     run loop
[self.hostReach startNotifier];
}
-(void)reachabilityChanged:(NSNotification *)note{
Reachability *currReach = [note object];
NSParameterAssert([currReach isKindOfClass:[Reachability class]]);
//             
NetworkStatus status = [currReach currentReachabilityStatus];
//                
self.isReachable = YES;
if(status == NotReachable){
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"      " message:nil delegate:nil cancelButtonTitle:@"  " otherButtonTitles:nil];
[alert show];
[alert release];
self.isReachable = NO;
return;
}
if (status==kReachableViaWiFi||status==kReachableViaWWAN) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"      " message:@"      " delegate:nil cancelButtonTitle:@"  " 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(@"     ");//          
}
else{
NSLog(@"      ");//          
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"      " message:nil delegate:nil cancelButtonTitle:@"  " otherButtonTitles:nil];
[alert show];
[alert release];
}
}

-(void)afn{
//1.           
AFNetworkReachabilityManager *manger = [AFNetworkReachabilityManager sharedManager];
//    ，    ，    block
[manger startMonitoring];
//2.    
[manger setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
/*
AFNetworkReachabilityStatusUnknown = -1,
AFNetworkReachabilityStatusNotReachable = 0,
AFNetworkReachabilityStatusReachableViaWWAN = 1,
AFNetworkReachabilityStatusReachableViaWiFi = 2,
*/
switch (status) {
case AFNetworkReachabilityStatusUnknown:
NSLog(@"  ");
break;
case AFNetworkReachabilityStatusNotReachable:
NSLog(@"    ");
break;
case AFNetworkReachabilityStatusReachableViaWWAN:
NSLog(@"3G|4G");
break;
case AFNetworkReachabilityStatusReachableViaWiFi:
NSLog(@"WiFi");
break;
default:
break;
}
}];
}