前言
在网络应用中，需要对用户设备的网络状态进行实时监控，有两个目的：
（1）让用户了解自己的网络状态，防止一些误会（比如怪应用无能）
（2）根据用户的网络状态进行智能处理，节省用户流量，提高用户体验
WIFI\3G网络：自动下载高清图片
低速网络：只下载缩略图
没有网络：只显示离线的缓存数据
最近在工作中遇到一个功能就是根据用户当前的网络状，用户未联网需要提示一下，如果是Wifi可以推荐一些图片新闻，如果是3G模式设置为无图的模式，获取网络状态比较简单，毕竟中国现在的流量还是一个比较贵的状态，哪天用户发现App消耗流量过多说不定就干掉了App 。 不过苹果的 Reachability 都解决了以上问题，使用起来也比较方便，所以就总结以下，具体的稍微简单分析下，下面话不多说，来一起看看详细的介绍：
示例代码
Reachability.h头文件代码:
#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
Reachability.m文件:
#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",
//当前网络2G/3G/4G蜂窝网络
(flags & kSCNetworkReachabilityFlagsIsWWAN) ? 'W' : '-',
//网络是否可达
(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;
}
//通过域名进行实例化 博客园-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;
}
//通过ip地址实例化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;
}
//检测是否能够直接连上互联网
+ (instancetype)reachabilityForInternetConnection
{
struct sockaddr_in zeroAddress;
bzero(&zeroAddress, sizeof(zeroAddress));
zeroAddress.sin_len = sizeof(zeroAddress);
zeroAddress.sin_family = AF_INET;
return [self reachabilityWithAddress:&zeroAddress];
}
//检测当前网络是否能够联上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函数为指定一个target
//当设备对于这个target链接状态发生改变时(比如断开链接，或者重新连上)，则回调reachabilityCallback函数，
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;
}
//获取当前网络状态
- (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
AppDelegate中的实现:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
//添加一个系统通知
[[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;
}
回调函数:
(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(@"====当前网络状态不可达=======http://www.cnblogs.com/xiaofeixiang");
break;
case ReachableViaWiFi:
NSLog(@"====当前网络状态为Wifi=======博客园-Fly_Elephant");
break;
case ReachableViaWWAN:
NSLog(@"====当前网络状态为3G=======keso");
break;
}
}
总结
以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作能带来一定的帮助，如果有疑问大家可以留言交流，谢谢大家对呐喊教程的支持。
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