如何使用可达性类来检测有效的互联网连接？
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【中文标题】如何使用可达性类来检测有效的互联网连接？【英文标题】：How to use reachability class to detect valid internet connection? 【发布时间】：2011-03-04 14:28:34 【问题描述】：我是 ios 开发的新手，正在努力让reachability.h 类正常工作。这是我的视图控制器代码：
- (void)viewWillAppear:(BOOL)animated
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:@selector(checkNetworkStatus:)
name:kReachabilityChangedNotification
object:nil];
internetReachable = [Reachability reachabilityForInternetConnection];
[internetReachable startNotifier];
- (void)checkNetworkStatus:(NSNotification *)notice
NetworkStatus internetStatus = [internetReachable currentReachabilityStatus];
NSLog(@"Network status: %i", internetStatus);
看起来不错，但在运行应用程序并切换到该视图时，xcode 控制台中没有出现任何内容。
我正在使用可达性 2.2 和 iOS 4.2。
有什么明显的我做错了吗？
【问题讨论】：
【参考方案1】：已编辑：如果您想在执行某些代码之前检查可访问性，您应该使用
Reachability *reachability = [Reachability reachabilityForInternetConnection];
NetworkStatus internetStatus = [reachability currentReachabilityStatus];
if (internetStatus != NotReachable)
//my web-dependent code
else
//there-is-no-connection warning
您还可以在某处添加可达性观察者（即在 viewDidLoad 中）：
Reachability *reachabilityInfo;
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(myReachabilityDidChangedMethod)
name:kReachabilityChangedNotification
object:reachabilityInfo];
当您不再需要可达性检测（即在dealloc 方法中）时，不要忘记调用[[NSNotificationCenter defaultCenter] removeObserver:self];。
【讨论】：
感谢您，但我收到一条错误消息，提示找不到 -isReachable。您的示例是否是旧版本的可达性？ 这可能会造成很大的麻烦。按需 *** 连接以及其他有问题的事情怎么样？ 当然不是必须的，但我无法想象没有任何可达性的良好网络服务相关应用【参考方案2】：这就是我的做法。我在我的 init 方法中设置了一个实例变量：
_reachability = [[APReachability reachabilityForInternetConnection] retain];
当我需要查询网络状态时，我会这样做：
NetworkStatus networkStatus = [_reachability currentReachabilityStatus];
if (networkStatus != NotReachable)
// Network related code
else
// No network code
如果你关心wifi等，网络状态可以是：
NotReachable // No network
ReachableViaWiFi // Reachable via Wifi
ReachableViaWWAN // Reachable via cellular
【讨论】：
【参考方案3】：更新：2013 年 11 月 4 日
在 iOS7 上使用 Reachability 3.0 版本
建立在@NR4TR 和@codecaffeine 的答案之上：
有 5 种方法可以做到这一点（未编译:)
#include <ifaddrs.h>
#include <arpa/inet.h>
//1 - Is www.apple.com reachable?
Reachability *rHostName = [Reachability reachabilityWithHostName:@"www.apple.com"];
NetworkStatus s1 = [rHostName currentReachabilityStatus];
//2 - Is local wifi router or access point reachable?
Reachability *rLocalWiFi = [Reachability reachabilityForLocalWiFi];
NetworkStatus s2 = [rLocalWiFi currentReachabilityStatus];
//3 - Is my access point connected to a router and the router connected to the internet?
Reachability *rConnection = [Reachability reachabilityForInternetConnection];
NetworkStatus s3 = [rConnection currentReachabilityStatus];
//4 IPv4 standard addresses checking instead of host to avoid dns lookup step
struct sockaddr_in saIPv4;
inet_pton(AF_INET, "74.125.239.51", &(saIPv4.sin_addr));
saIPv4.sin_len = sizeof(saIPv4);
saIPv4.sin_family = AF_INET;
Reachability *rIPv4 = [Reachability reachabilityWithAddress:&saIPv4];
NetworkStatus s4 = [rIPv4 currentReachabilityStatus];
//5 IPv6 addresses checking instead of host to avoid dns lookup step
struct sockaddr_in saIPv6;
inet_pton(AF_INET, "2607:f8b0:4010:801::1014", &(saIPv6.sin_addr));
saIPv6.sin_len = sizeof(saIPv6);
saIPv6.sin_family = AF_INET;
Reachability *rIPv6 = [Reachability reachabilityWithAddress:&saIPv6];
NetworkStatus s5 = [rIPv6 currentReachabilityStatus];
处理状态相同
if (ReachableViaWiFi == s1)
return @"WiFi"; //@"WLAN"
if (ReachableViaWWAN == s1)
return @"Cellular"; //@"WWAN"
return @"None";
【讨论】：
【参考方案4】：点击这个链接，它有非常有用的源代码和步骤 https://github.com/tonymillion/Reachability。 这为您提供了有关如何在 Reachability 中使用不同方法进行游戏的信息。
添加 system.configuration.framewok，并将 Reachability.m 和 Reachability.h 文件添加到您的项目中。使用后有类似的方法
+(instancetype)reachabilityWithHostName:(NSString*)hostname;
+(instancetype)reachabilityForInternetConnection;
+(instancetype)reachabilityWithAddress:(void *)hostAddress;
+(instancetype)reachabilityForLocalWiFi;
示例 sn-p：
- (void)CheckConnection
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(reachabilityChanged:)
name:kReachabilityChangedNotification
object:nil];
Reachability * reach = [Reachability reachabilityWithHostname:@"www.google.com"];
reach.reachableBlock = ^(Reachability * reachability)
dispatch_async(dispatch_get_main_queue(), ^
_blockLabel.stringValue = @"Block Says Reachable";
);
;
reach.unreachableBlock = ^(Reachability * reachability)
dispatch_async(dispatch_get_main_queue(), ^
_blockLabel.stringValue = @"Block Says Unreachable";
);
;
[reach startNotifier];
希望对你有帮助
【讨论】：
【参考方案5】：只需导入可达性类，然后
-(BOOL) connectedToNetwork
const char *host_name = "www.google.com";
BOOL _isDataSourceAvailable = NO;
Boolean success;
SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL,host_name);
SCNetworkReachabilityFlags flags;
success = SCNetworkReachabilityGetFlags(reachability, &flags);
_isDataSourceAvailable = success &&
(flags & kSCNetworkFlagsReachable) &&
!(flags & kSCNetworkFlagsConnectionRequired);
CFRelease(reachability);
return _isDataSourceAvailable;
【讨论】：
【参考方案6】：参考下面的代码检查Internet Connectivity：
struct sockaddr_in zeroAddress;
bzero(&zeroAddress, sizeof(zeroAddress));
zeroAddress.sin_len = sizeof(zeroAddress);
zeroAddress.sin_family = AF_INET;
// Recover reachability flags
SCNetworkReachabilityRef defaultRouteReachability = SCNetworkReachabilityCreateWithAddress(NULL, (struct sockaddr*)&zeroAddress);
SCNetworkReachabilityFlags flags;
BOOL didRetrieveFlags = SCNetworkReachabilityGetFlags(defaultRouteReachability, &flags);
CFRelease(defaultRouteReachability);
if (!didRetrieveFlags)
return 0;
BOOL isReachable = flags & kSCNetworkFlagsReachable;
BOOL needsConnection = flags & kSCNetworkFlagsConnectionRequired;
BOOL nonWiFi = flags & kSCNetworkReachabilityFlagsTransientConnection;
NSURL *testURL = [NSURL URLWithString:@"http://www.google.com/"];
NSURLRequest *testRequest = [NSURLRequest requestWithURL:testURL cachePolicy:NSURLRequestReloadIgnoringLocalCacheData timeoutInterval:20.0];
NSURLResponse *response = nil;
NSError *error = nil;
NSData *connectiondata = [NSURLConnection sendSynchronousRequest:testRequest
returningResponse:&response
BOOL connection=NO;
if ([connectiondata length] > 0 &&
error == nil)
NSLog(@"Connection present” );
connection=YES;
else
NSLog(@"No Connection" );
connection=NO;
return ((isReachable && !needsConnection) || nonWiFi) ? (connection ? YES : NO) : NO;
【讨论】：
【参考方案7】：最简单的方法（一旦您将Reachability 添加到您的项目中）：
Reachability *reachability = [Reachability reachabilityForInternetConnection];
if (reachability.isReachable)
NSLog(@"We have internet!");
else
NSLog(@"No internet!");
【讨论】：
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