#import <Foundation/Foundation.h> #import <SystemConfiguration/SystemConfiguration.h> #import <netinet/in.h>  //http://www.cnblogs.com/xiaofeixiang typedef enum : NSInteger {  NotReachable = 0,  ReachableViaWiFi,  ReachableViaWWAN } NetworkStatus;   extern NSString *kReachabilityChangedNotification;   @interface Reachability : NSObject  /*!  * Use to check the reachability of a given host name.  */ + (instancetype)reachabilityWithHostName:(NSString *)hostName;  /*!  * Use to check the reachability of a given IP address.  */ + (instancetype)reachabilityWithAddress:(const struct sockaddr_in *)hostAddress;  /*!  * Checks whether the default route is available. Should be used by applications that do not connect to a particular host.  */ + (instancetype)reachabilityForInternetConnection;  /*!  * Checks whether a local WiFi connection is available.  */ + (instancetype)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

#import <arpa/inet.h> #import <ifaddrs.h> #import <netdb.h> #import <sys/socket.h> #import <CoreFoundation/CoreFoundation.h> #import "Reachability.h" NSString *kReachabilityChangedNotification = @"kNetworkReachabilityChangedNotification"; #pragma mark - Supporting functions #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",   //當前網絡2G/3G/4G蜂窩網絡   (flags & kSCNetworkReachabilityFlagsIsWWAN)    ? 'W' : '-',   //網絡是否可達   (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 } static void ReachabilityCallback(SCNetworkReachabilityRef target, SCNetworkReachabilityFlags flags, void* info) { #pragma unused (target, flags)  NSCAssert(info != NULL, @"info was NULL in ReachabilityCallback");  NSCAssert([(__bridge NSObject*) info isKindOfClass: [Reachability class]], @"info was wrong class in ReachabilityCallback");  //http://www.cnblogs.com/xiaofeixiang  Reachability* noteObject = (__bridge Reachability *)info;  // Post a notification to notify the client that the network reachability changed.  [[NSNotificationCenter defaultCenter] postNotificationName: kReachabilityChangedNotification object: noteObject]; } #pragma mark - Reachability implementation @implementation Reachability {  BOOL _alwaysReturnLocalWiFiStatus; //default is NO  SCNetworkReachabilityRef _reachabilityRef; } //通過域名進行實例化 博客園-Fly_Elephant + (instancetype)reachabilityWithHostName:(NSString *)hostName {  Reachability* returnValue = NULL;  SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL, [hostName UTF8String]);  if (reachability != NULL)  {  returnValue= [[self alloc] init];  if (returnValue != NULL)  {   returnValue->_reachabilityRef = reachability;   returnValue->_alwaysReturnLocalWiFiStatus = NO;  }  }  return returnValue; } //通過ip地址實例化Reachability + (instancetype)reachabilityWithAddress:(const struct sockaddr_in *)hostAddress {  SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, (const struct sockaddr *)hostAddress);  Reachability* returnValue = NULL;  if (reachability != NULL)  {  returnValue = [[self alloc] init];  if (returnValue != NULL)  {   returnValue->_reachabilityRef = reachability;   returnValue->_alwaysReturnLocalWiFiStatus = NO;  }  }  return returnValue; } //檢測是否能夠直接連上互聯網 + (instancetype)reachabilityForInternetConnection {  struct sockaddr_in zeroAddress;  bzero(&zeroAddress, sizeof(zeroAddress));  zeroAddress.sin_len = sizeof(zeroAddress);  zeroAddress.sin_family = AF_INET;  return [self reachabilityWithAddress:&zeroAddress]; } //檢測當前網絡是否能夠聯上wifi + (instancetype)reachabilityForLocalWiFi {  struct sockaddr_in localWifiAddress;  bzero(&localWifiAddress, sizeof(localWifiAddress));  localWifiAddress.sin_len = sizeof(localWifiAddress);  localWifiAddress.sin_family = AF_INET;  // IN_LINKLOCALNETNUM is defined in <netinet/in.h> as 169.254.0.0.  localWifiAddress.sin_addr.s_addr = htonl(IN_LINKLOCALNETNUM);  Reachability* returnValue = [self reachabilityWithAddress: &localWifiAddress];  if (returnValue != NULL)  {  returnValue->_alwaysReturnLocalWiFiStatus = YES;  }  return returnValue; } #pragma mark - Start and stop notifier - (BOOL)startNotifier {  BOOL returnValue = NO;  SCNetworkReachabilityContext context = {0, (__bridge voidvoid *)(self), NULL, NULL, NULL};  //SCNetworkReachabilitySetCallback函數為指定一個target  //當設備對于這個target鏈接狀態發生改變時(比如斷開鏈接，或者重新連上)，則回調reachabilityCallback函數，  if (SCNetworkReachabilitySetCallback(_reachabilityRef, ReachabilityCallback, &context))  {  if (SCNetworkReachabilityScheduleWithRunLoop(_reachabilityRef, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode))  {   returnValue = YES;  }  }  return returnValue; } - (void)stopNotifier {  if (_reachabilityRef != NULL)  {  SCNetworkReachabilityUnscheduleFromRunLoop(_reachabilityRef, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);  } } - (void)dealloc {  [self stopNotifier];  if (_reachabilityRef != NULL)  {  CFRelease(_reachabilityRef);  } } #pragma mark - Network Flag Handling - (NetworkStatus)localWiFiStatusForFlags:(SCNetworkReachabilityFlags)flags {  PrintReachabilityFlags(flags, "localWiFiStatusForFlags");  NetworkStatus returnValue = NotReachable;  if ((flags & kSCNetworkReachabilityFlagsReachable) && (flags & kSCNetworkReachabilityFlagsIsDirect))  {  returnValue = ReachableViaWiFi;  }  return returnValue; } - (NetworkStatus)networkStatusForFlags:(SCNetworkReachabilityFlags)flags {  PrintReachabilityFlags(flags, "networkStatusForFlags");  if ((flags & kSCNetworkReachabilityFlagsReachable) == 0)  {  // The target host is not reachable.  return NotReachable;  }  NetworkStatus returnValue = NotReachable;  if ((flags & kSCNetworkReachabilityFlagsConnectionRequired) == 0)  {  /*   If the target host is reachable and no connection is required then we'll assume (for now) that you're on Wi-Fi...   */  returnValue = 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...   */   returnValue = ReachableViaWiFi;  }  }  if ((flags & kSCNetworkReachabilityFlagsIsWWAN) == kSCNetworkReachabilityFlagsIsWWAN)  {  /*   ... but WWAN connections are OK if the calling application is using the CFNetwork APIs.   */  returnValue = ReachableViaWWAN;  }  return returnValue; } - (BOOL)connectionRequired {  NSAssert(_reachabilityRef != NULL, @"connectionRequired called with NULL reachabilityRef");  SCNetworkReachabilityFlags flags;  if (SCNetworkReachabilityGetFlags(_reachabilityRef, &flags))  {  return (flags & kSCNetworkReachabilityFlagsConnectionRequired);  }  return NO; } //獲取當前網絡狀態 - (NetworkStatus)currentReachabilityStatus {  NSAssert(_reachabilityRef != NULL, @"currentNetworkStatus called with NULL SCNetworkReachabilityRef");  NetworkStatus returnValue = NotReachable;  SCNetworkReachabilityFlags flags;  if (SCNetworkReachabilityGetFlags(_reachabilityRef, &flags))  {  if (_alwaysReturnLocalWiFiStatus)  {   returnValue = [self localWiFiStatusForFlags:flags];  }  else  {   returnValue = [self networkStatusForFlags:flags];  }  }  return returnValue; } @end

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {  //添加一個系統通知  [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reachabilityChanged:) name:kReachabilityChangedNotification object:nil];  //初始化  self.internetReachability=[Reachability reachabilityForInternetConnection];  //通知添加到Run Loop  [self.internetReachability startNotifier];  [self updateInterfaceWithReachability:_internetReachability];  return YES; } 

(void) reachabilityChanged:(NSNotification *)note {  Reachability* curReach = [note object];  NSParameterAssert([curReach isKindOfClass:[Reachability class]]);  [self updateInterfaceWithReachability:curReach]; } - (void)updateInterfaceWithReachability:(Reachability *)reachability {  NetworkStatus netStatus = [reachability currentReachabilityStatus];  switch (netStatus) {  case NotReachable:   NSLog(@"====當前網絡狀態不可達=======http://www.cnblogs.com/xiaofeixiang");   break;  case ReachableViaWiFi:   NSLog(@"====當前網絡狀態為Wifi=======博客園-Fly_Elephant");   break;  case ReachableViaWWAN:   NSLog(@"====當前網絡狀態為3G=======keso");   break;  } }