iphone - 如何检查 iPhone 的网络连接

Question

此代码用于检查互联网连接是否可用。如果互联网连接可用，则应从服务器数据库验证用户名和密码，即应调用发送请求方法，如果没有，则应从本地验证用户名和密码数据库，即检查方法应该被调用。但是这里的问题是当互联网关闭时，它也会进入发送请求方法而不是进入检查网络。可能是什么问题。请帮助我解决这个问题。我添加了可达性文件并导入了 CFNetwork.framework。

- (void) showNetWorkAlert { 

   [UIApplication sharedApplication].networkActivityIndicatorVisible = NO; 
   UIAlertView *networkAlert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"Network connection unavailable." 
                                            delegate:self cancelButtonTitle:@"OK" otherButtonTitles:@"Retry", nil]; 
   [networkAlert show]; 
   [networkAlert release]; 
} 



#pragma mark To Check Network Connection. 
- (BOOL) currentNetworkStatus { 
   [UIApplication sharedApplication].networkActivityIndicatorVisible = YES; 
   BOOL connected; 
   const char *host = "www.apple.com"; 
   SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL, host); 
   SCNetworkReachabilityFlags flags; 
   connected = SCNetworkReachabilityGetFlags(reachability, &flags); 
   BOOL isConnected = YES; 
   isConnected = connected && (flags & kSCNetworkFlagsReachable) && !(flags & kSCNetworkFlagsConnectionRequired); 
   CFRelease(reachability); 

   if(!isConnected) { 
      // sleep(1); 
      [self showNetWorkAlert]; 
      //[self check];
   } 
   else 
      return isConnected; 
   //[self sendRequest];
   return isConnected; 
}


-(IBAction)buttonPressed:(id)sender
{
   //[self sendRequest];
   //[[Reachability sharedReachability] setHostName:kHostName];
   //Set Reachability class to notifiy app when the network status changes.
   //[[Reachability sharedReachability] setNetworkStatusNotificationsEnabled:YES];
   //Set a method to be called when a notification is sent.
   //[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:@"kNetworkReachabilityChangedNotification" object:nil];
   //[self updateStatus];
   //[self sendRequest];
   //NSLog(<#NSString *format#>)
   //this is to select username and password from database.
   //[self check];
   if ([self currentNetworkStatus]) { 
      [self sendRequest];
   }
   else {
      [self check];
   }





}

Answer 1

Rocky，你的代码是正确的。只需检查 URL 是否正确。还有其他方法在按钮上检查主机，如下所示

[[NSNotificationCenter defaultCenter] addObserver:self
                                                 selector:@selector(reachabilityChanged:)
                                                     name:kReachabilityChangedNotification
                                                   object:nil];

        hostReach = [[Reachability reachabilityWithHostName:@"www.google.com"]retain];
        [hostReach startNotifier];

并在 (reachabilityChanged:) 方法调用中像这样

-(void)reachabilityChanged:(NSNotification*)note
{
    static BOOL showNotConnnected =NO;
    Reachability *curReach =[note object];
    NSParameterAssert([curReach isKindOfClass:[Reachability class]]);
    NetworkStatus netStatus = [curReach currentReachabilityStatus];
    if(netStatus != NotReachable)
    {
        UIAlertView *notconnect1 = [[UIAlertView alloc]initWithTitle:@"Server is  connected" message:@"Server is connected" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:@"Cancel",nil];
        [notconnect1 show];
        [notconnect1 release];

    }
    else if(showNotConnnected == NO)
    {
        showNotConnnected =YES;
        UIAlertView *notconnect = [[UIAlertView alloc]initWithTitle:@"Server is Not connected" message:@"Server may be slow or not connected" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:@"Cancel",nil];
        [notconnect show];
        [notconnect release];
    }
}

希望这对你有帮助