import

typedef enum { NotReachable = 0, ReachableViaWiFi, ReachableViaWWAN } NetworkStatus;

define kReachabilityChangedNotification @"kNetworkReachabilityChangedNotification"

@interface Reachability: NSObject { BOOL localWiFiRef; SCNetworkReachabilityRef reachabilityRef; }

//reachabilityWithHostName- Use to check the reachability of a particular host name.

(Reachability) reachabilityWithHostName: (NSString) hostName;

//reachabilityWithAddress- Use to check the reachability of a particular IP address.

(Reachability) reachabilityWithAddress: (const struct sockaddr_in) hostAddress;

//reachabilityForInternetConnection- checks whether the default route is available.
// Should be used by applications that do not connect to a particular host

(Reachability*) reachabilityForInternetConnection;

//reachabilityForLocalWiFi- checks whether a local wifi connection is available.

(Reachability*) reachabilityForLocalWiFi;

//Start listening for reachability notifications on the current run loop

(BOOL) startNotifier;

(void) stopNotifier;

(NetworkStatus) currentReachabilityStatus; //WWAN may be available, but not active until a connection has been established. //WiFi may require a connection for VPN on Demand.

(BOOL) connectionRequired; @end

//Reachability.m

import

import "Reachability.h"

define kShouldPrintReachabilityFlags 1

static void PrintReachabilityFlags(SCNetworkReachabilityFlags flags, const char* comment) {

if kShouldPrintReachabilityFlags

NSLog(@"Reachability Flag Status: %c%c %c%c%c%c%c%c%c %s\n",        (flags & kSCNetworkReachabilityFlagsIsWWAN)                  ? 'W' : '-',        (flags & kSCNetworkReachabilityFlagsReachable)            ? 'R' : '-',        (flags & kSCNetworkReachabilityFlagsTransientConnection)  ? 't' : '-',        (flags & kSCNetworkReachabilityFlagsConnectionRequired)   ? 'c' : '-',        (flags & kSCNetworkReachabilityFlagsConnectionOnTraffic)  ? 'C' : '-',        (flags & kSCNetworkReachabilityFlagsInterventionRequired) ? 'i' : '-',        (flags & kSCNetworkReachabilityFlagsConnectionOnDemand)   ? 'D' : '-',        (flags & kSCNetworkReachabilityFlagsIsLocalAddress)       ? 'l' : '-',        (flags & kSCNetworkReachabilityFlagsIsDirect)             ? 'd' : '-',        comment        );

endif

}

@implementation Reachability static void ReachabilityCallback(SCNetworkReachabilityRef target, SCNetworkReachabilityFlags flags, void* info) {

pragma unused (target, flags)

NSCAssert(info != NULL, @"info was NULL in ReachabilityCallback");NSCAssert([(NSObject*) info isKindOfClass: [Reachability class]], @"info was wrong class in ReachabilityCallback");//We're on the main RunLoop, so an NSAutoreleasePool is not necessary, but is added defensively// in case someon uses the Reachablity object in a different thread.NSAutoreleasePool* myPool = [[NSAutoreleasePool alloc] init];Reachability* noteObject = (Reachability*) info;// Post a notification to notify the client that the network reachability changed.[[NSNotificationCenter defaultCenter] postNotificationName: kReachabilityChangedNotification object: noteObject];[myPool release];

}

(BOOL) startNotifier { BOOL retVal = NO; SCNetworkReachabilityContext context = {0, self, NULL, NULL, NULL}; if(SCNetworkReachabilitySetCallback(reachabilityRef, ReachabilityCallback, &context)) { if(SCNetworkReachabilityScheduleWithRunLoop(reachabilityRef, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode)) { retVal = YES; } } return retVal; }

(void) stopNotifier { if(reachabilityRef!= NULL) { SCNetworkReachabilityUnscheduleFromRunLoop(reachabilityRef, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode); } }

(void) dealloc { [self stopNotifier]; if(reachabilityRef!= NULL) { CFRelease(reachabilityRef); } [super dealloc]; }

(Reachability) reachabilityWithHostName: (NSString) hostName; { Reachability* retVal = NULL; SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL, [hostName UTF8String]); if(reachability!= NULL) { retVal= [[[self alloc] init] autorelease]; if(retVal!= NULL) { retVal->reachabilityRef = reachability; retVal->localWiFiRef = NO; } } return retVal; }

(Reachability) reachabilityWithAddress: (const struct sockaddr_in) hostAddress; { SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, (const struct sockaddr)hostAddress); Reachability retVal = NULL; if(reachability!= NULL) { retVal= [[[self alloc] init] autorelease]; if(retVal!= NULL) { retVal->reachabilityRef = reachability; retVal->localWiFiRef = NO; } } return retVal; }

(Reachability*) reachabilityForInternetConnection; { struct sockaddr_in zeroAddress; bzero(&zeroAddress, sizeof(zeroAddress)); zeroAddress.sin_len = sizeof(zeroAddress); zeroAddress.sin_family = AF_INET; return [self reachabilityWithAddress: &zeroAddress]; }

(Reachability) reachabilityForLocalWiFi; { struct sockaddr_in localWifiAddress; bzero(&localWifiAddress, sizeof(localWifiAddress)); localWifiAddress.sin_len = sizeof(localWifiAddress); localWifiAddress.sin_family = AF_INET; // IN_LINKLOCALNETNUM is defined in as 169.254.0.0 localWifiAddress.sin_addr.s_addr = htonl(IN_LINKLOCALNETNUM); Reachability retVal = [self reachabilityWithAddress: &localWifiAddress]; if(retVal!= NULL) { retVal->localWiFiRef = YES; } return retVal; }

pragma mark Network Flag Handling

(NetworkStatus) localWiFiStatusForFlags: (SCNetworkReachabilityFlags) flags { PrintReachabilityFlags(flags, "localWiFiStatusForFlags");

BOOL retVal = NotReachable; if((flags & kSCNetworkReachabilityFlagsReachable) && (flags & kSCNetworkReachabilityFlagsIsDirect)) { retVal = ReachableViaWiFi;
} return retVal; }

(NetworkStatus) networkStatusForFlags: (SCNetworkReachabilityFlags) flags { PrintReachabilityFlags(flags, "networkStatusForFlags"); if ((flags & kSCNetworkReachabilityFlagsReachable) == 0) { // if target host is not reachable return NotReachable; }

BOOL retVal = NotReachable;

if ((flags & kSCNetworkReachabilityFlagsConnectionRequired) == 0) { // if target host is reachable and no connection is required // then we'll assume (for now) that your on Wi-Fi retVal = ReachableViaWiFi; }

if ((((flags & kSCNetworkReachabilityFlagsConnectionOnDemand ) != 0) || (flags & kSCNetworkReachabilityFlagsConnectionOnTraffic) != 0)) { // ... and the connection is on-demand (or on-traffic) if the // calling application is using the CFSocketStream or higher APIs
```
    if ((flags & kSCNetworkReachabilityFlagsInterventionRequired) == 0)    {        // ... and no [user] intervention is needed        retVal = ReachableViaWiFi;    }}
```
if ((flags & kSCNetworkReachabilityFlagsIsWWAN) == kSCNetworkReachabilityFlagsIsWWAN) { // ... but WWAN connections are OK if the calling application // is using the CFNetwork (CFSocketStream?) APIs. retVal = ReachableViaWWAN; } return retVal; }

(BOOL) connectionRequired; { NSAssert(reachabilityRef != NULL, @"connectionRequired called with NULL reachabilityRef"); SCNetworkReachabilityFlags flags; if (SCNetworkReachabilityGetFlags(reachabilityRef, &flags)) { return (flags & kSCNetworkReachabilityFlagsConnectionRequired); } return NO; }

(NetworkStatus) currentReachabilityStatus { NSAssert(reachabilityRef != NULL, @"currentNetworkStatus called with NULL reachabilityRef"); NetworkStatus retVal = NotReachable; SCNetworkReachabilityFlags flags; if (SCNetworkReachabilityGetFlags(reachabilityRef, &flags)) { if(localWiFiRef) { retVal = [self localWiFiStatusForFlags: flags]; } else { retVal = [self networkStatusForFlags: flags]; } } return retVal; } @end

//appcontroller

(BOOL)application:(UIApplication )application didFinishLaunchingWithOptions:(NSDictionary )launchOptions{ ..... //连接到自己的服务器 [[NSNotificationCenter defaultCenter] addObserver: self selector: @selector(reachabilityChanged:) name: kReachabilityChangedNotification object: nil]; struct sockaddr_in addr; string host=string("192.168.221.1"); u_short port=9394; const char _host = host.c_str(); addr.sin_family = AF_INET; addr.sin_addr.s_addr = inet_addr(_host); if (addr.sin_addr.s_addr == INADDR_NONE) { hostent h = gethostbyname(_host); if (h) { addr.sin_addr.s_addr = (ulong)h->h_addr_list[0]; } } addr.sin_port = htons(port); bzero(&(addr.sin_zero), 8); firstComeIn=true; hostReach = [[Reachability reachabilityWithAddress:&addr] retain]; [hostReach startNotifier]; }

//网络状态改变

(void) reachabilityChanged: (NSNotification )note { Reachability curReach = [note object]; NSParameterAssert([curReach isKindOfClass: [Reachability class]]); [self updateInterfaceWithReachability:curReach];

} -(void) updateInterfaceWithReachability:(Reachability*) curReach { NetworkStatus netStatus = [curReach currentReachabilityStatus]; //BOOL connectionRequired= [curReach connectionRequired]; if(firstComeIn){ firstComeIn=false; return; } switch (netStatus) { case NotReachable: //没有连接 {

        break;    }    case ReachableViaWWAN: //3g/GPRS    {        break;    }    case ReachableViaWiFi:  //wifi    {        break;    }}

本文转自卓行天下 51CTO博客，原文链接：http://blog.51cto.com/9951038/1751903，如需转载请自行联系原作者