iOS之 网络连接监测框架 Reachability

介绍一款简单好用的网络连接监测框架的使用

名字是Reachability

这个框架有很多用途，这里我只说简单的用法

---

先看一下这个框架

Reachability.h

#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

//用于检查给定主机名的可达性。
+ (instancetype)reachabilityWithHostName:(NSString *)hostName;


//用来检查一个给定的IP地址的可达性。

+ (instancetype)reachabilityWithAddress:(const struct sockaddr_in *)hostAddress;


//检查默认路由是否可用。应使用不连接到特定主机的应用程序。

+ (instancetype)reachabilityForInternetConnection;

//检查本地WiFi连接是可用的。

+ (instancetype)reachabilityForLocalWiFi;

//开始监听当前运行循环上的可达性通知。

- (BOOL)startNotifier;
- (void)stopNotifier;

- (NetworkStatus)currentReachabilityStatus;


//广域网可能是可用的，但不会主动建立连接。无线网络可能需要连接VPN的需求。

- (BOOL)connectionRequired;

@end

---

Reachability.m

#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",
          (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;
}


@end

然后在你的AppDelegate.m里导入头文件“Reachability.h”就可以用

不关模拟器的情况下，你试着断网和联网看看效果

#import "AppDelegate.h"
#import "Reachability.h"
@interface AppDelegate ()
//定义属性
@property(nonatomic,strong)Reachability *reachability;
@end

@implementation AppDelegate


- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

    //创建通知
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(internetConnection) name:kReachabilityChangedNotification object:nil];

    //初始化可达性
    self.reachability =[Reachability reachabilityForInternetConnection];

    //开始监听
    [self.reachability startNotifier];
    [self internetConnection];
    return YES;
}

-(void)internetConnection
{   //网络连接现状
    NetworkStatus status =[self.reachability currentReachabilityStatus];
    switch (status) {
        case NotReachable:
            NSLog(@"没有网络");
            break;
        case ReachableViaWiFi:
            NSLog(@"wifi连接");
            break;
        case ReachableViaWWAN:
             NSLog(@"移动蜂窝网络");
            break;
        default:
            break;
    }

}

Demo下载 ： GitHub NetworkConnectionState