Objective c 如何使用可达性类检测有效的internet连接？_Objective C_Ios_Ios4_Reachability

Objective c 如何使用可达性类检测有效的internet连接？

objective-c ios ios4

Objective c 如何使用可达性类检测有效的internet连接？,objective-c,ios,ios4,reachability,Objective C,Ios,Ios4,Reachability,我是iOS开发新手，正在努力让可达性.h类正常工作。以下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

我是iOS开发新手，正在努力让可达性.h类正常工作。以下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);
}

它看起来不错，但在运行应用程序并切换到该视图时，xcode控制台中没有显示任何内容

我正在使用可达性2.2和iOS 4.2

有什么明显的错误吗？

编辑：如果您想在执行某些代码之前检查可达性，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）：

不要忘记调用

[[NSNotificationCenter defaultCenter]removeObserver:self]当您不再需要可达性检测时（即在dealloc
方法中）。
以下是我的操作方法。我在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：
NetworkStatus networkStatus = [_reachability currentReachabilityStatus];
if (networkStatus != NotReachable) {
    // Network related code
}
else {
    // No network code
}

如果您关心wifi等，网络状态可以是：
    NotReachable // No network
    ReachableViaWiFi // Reachable via Wifi
    ReachableViaWWAN // Reachable via cellular

更新：2013年11月4日
在iOS7上使用可达性3.0版本
要在@NR4TR和@codecaffine的答案之上构建：
有5种方法可以做到这一点（未编译：）
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;
}

请参阅下面的代码以检查互联网连接：
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;

遵循这个链接，它有非常有用的源代码和步骤
.
这为您提供了有关如何在可达性中使用不同方法的信息
添加system.configuration.framewok，并将Reachability.m和Reachability.h文件添加到项目中。有使用后的方法，如
+(instancetype)reachabilityWithHostName:(NSString*)hostname;
+(instancetype)reachabilityForInternetConnection;
+(instancetype)reachabilityWithAddress:(void *)hostAddress;
+(instancetype)reachabilityForLocalWiFi;

示例代码段：
- (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];
}

希望这有助于最简单的方法（一旦添加到项目中）：
感谢您的帮助，但我收到一个错误消息-isReachable未找到。你的例子是旧版本的可达性吗？这可能会引起很大的麻烦。按需VPN连接和其他有问题的东西怎么样？当然这不是必须的，但我无法想象没有任何可达性的使用，好的web服务相关应用程序
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;

+(instancetype)reachabilityWithHostName:(NSString*)hostname;
+(instancetype)reachabilityForInternetConnection;
+(instancetype)reachabilityWithAddress:(void *)hostAddress;
+(instancetype)reachabilityForLocalWiFi;

- (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];
}

Reachability *reachability = [Reachability reachabilityForInternetConnection];
if (reachability.isReachable) {
    NSLog(@"We have internet!");
} else {
    NSLog(@"No internet!");
}