How to perform validation of online connection in iphone

i have two database one database in webserver and other database in local here i have to cheek in device if online connection is on then data should come from webserver database 开发者_StackOverflow中文版if online is off then data is come from sqlite local database and diplay data on iphone please help me in this problem

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Add reachabilty.m and reachabilty.h to your project. In your controller which is active throughout the life of the program add the following lines and use the below callback.

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

    internetReachable = [[Reachability reachabilityForInternetConnection] retain];
    [internetReachable startNotifier];

    // check if a pathway to a random host exists
    hostReachable = [[Reachability reachabilityWithHostName: @"www.apple.com"] retain];
    [hostReachable startNotifier];

The callback is as follows:

- (void) checkNetworkStatus:(NSNotification *)notice
{
    // called after network status changes

    NetworkStatus internetStatus = [internetReachable currentReachabilityStatus];
    switch (internetStatus)

    {
        case NotReachable:
        {
            break;

        }
        case ReachableViaWiFi:
        {
            break;

        }
        case ReachableViaWWAN:
        {
            break;

        }
    }

    NetworkStatus hostStatus = [hostReachable currentReachabilityStatus];
    switch (hostStatus)

    {
        case NotReachable:
        {
            break;

        }
        case ReachableViaWiFi:
        {
            break;

        }
        case ReachableViaWWAN:
        {
            break;

        }
    }
}

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In your appDelegate header file

NetworkStatus remoteHostStatus;
NetworkStatus internetConnectionStatus;
NetworkStatus localWiFiConnectionStatus;
@property NetworkStatus remoteHostStatus;
@property NetworkStatus internetConnectionStatus;
@property NetworkStatus localWiFiConnectionStatus;

in your appDelegate .m file

- (void)updateStatus
{
    self.remoteHostStatus           = [[Reachability sharedReachability] remoteHostStatus];
    self.internetConnectionStatus   = [[Reachability sharedReachability] internetConnectionStatus];
    self.localWiFiConnectionStatus  = [[Reachability sharedReachability] localWiFiConnectionStatus];
}

- (BOOL)isCarrierDataNetworkActive
{
    return (self.remoteHostStatus == ReachableViaCarrierDataNetwork);
}

- (NSString *)hostName
{
    return @"www.apple.com";
}
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{  
    [[Reachability sharedReachability] setHostName:[self hostName]];
    [[NSNotificationCenter defaultCenter] addObserver:self 
                                             selector:@selector(reachabilityChanged:) 
                                                 name:@"kNetworkReachabilityChangedNotification" 
                                               object:nil];
}

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Use Reachability for network related information. See apple's sample of reachability.