使用 Reachability 获取网络状态

Reachability

source https://developer.apple.com/library/ios/samplecode/Reachability/Introduction/Intro.html

reachability 为苹果官方demo提供的一个检测网络状态的代码,下载源码后本人对其进行了修改,修改后源码:

reachability.h  +  reachability.m

#import <Foundation/Foundation.h>
#import <SystemConfiguration/SystemConfiguration.h>
#import <netinet/in.h>


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;

/*!
 *  测试是否能连接网
 */
+ (NetworkStatus)isExistNetwork;

@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
",
          (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
}


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");

    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;
}

+ (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;
}


+ (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;
}



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


+ (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 void *)(self), NULL, NULL, NULL};

    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;
}


- (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;
}


+ (NetworkStatus)isExistNetwork
{
    NetworkStatus isExistenceNetwork;
    
    //单例
    static Reachability *reachability = nil;
    
    //服务器地址选择了百度
    if (reachability == nil)
    {
        reachability = [Reachability reachabilityWithHostName:@"www.baidu.com"];
    }
    
    switch([reachability currentReachabilityStatus]) {
        case NotReachable:
            isExistenceNetwork = NotReachable;
            break;
        case ReachableViaWWAN:
            isExistenceNetwork = ReachableViaWWAN;
            break;
        case ReachableViaWiFi:
            isExistenceNetwork = ReachableViaWiFi;
            break;
    }
    
    return  isExistenceNetwork;
}

@end

直接使用下面的代码来得到网络信息,是单例模式,无需担心浪费内存

    [Reachability isExistNetwork];

其返回3个枚举值,判断一下即可,

    NotReachable, ReachableViaWiFi, ReachableViaWWAN

使用通知来监听网络状态

1.定义属性(strong)

@property (nonatomic, strong) Reachability *hostReachability;
@property (nonatomic, strong) Reachability *internetReachability;
@property (nonatomic, strong) Reachability *wifiReachability;

2.指定监听的方法

- (void) reachabilityChanged:(NSNotification *)note
{
    Reachability *tmp = [note object];
    
    NSLog(@"%d", [tmp currentReachabilityStatus]);
}

3.初始化以及监听

    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(reachabilityChanged:)
                                                 name:kReachabilityChangedNotification
                                               object:nil];
    
    NSString *remoteHostName = @"www.baidu.com";
    _hostReachability = [Reachability reachabilityWithHostName:remoteHostName];
    [_hostReachability startNotifier];
    
    _internetReachability = [Reachability reachabilityForInternetConnection];
    [_internetReachability startNotifier];
    
    _wifiReachability = [Reachability reachabilityForLocalWiFi];
    [_wifiReachability startNotifier];