最近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，具体的稍微简单分析一下。
Reachability.h头文件代码:
Reachability.m文件:
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#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
void
*)(
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
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AppDelegate中的实现:
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- (
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
;
}
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回调函数:
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- (
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
;
}
}
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模式测试 Wifi模式-wuWifi-连接Wifi，显示结果如下:
如果直接通过host实例化也可以:
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NSString
*remoteHostName = @
"www.cnblogs.com/xiaofeixiang"
;
self
.hostReachability = [Reachability reachabilityWithHostName:remoteHostName];
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