iOS判斷當前是否有網絡

[轉自]：http://blog.csdn.net/zengraoli/article/details/12873329

在對應的.h文件中加入聲明：

- (BOOL) connectedToNetwork;

如果方法前面加+，就相當於類的靜態方法，這裏要注意一下

在.m中加入定義：

-(BOOL) connectedToNetwork
{
    // Create zero addy
    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)
    {
        printf("Error. Could not recover network reachability flags\n");
        return NO;
    }

    BOOL isReachable = ((flags & kSCNetworkFlagsReachable) != 0);
    BOOL needsConnection = ((flags & kSCNetworkFlagsConnectionRequired) != 0);
    return (isReachable && !needsConnection) ? YES : NO;
}

在調用的時候，在對應的按鈕中加入判斷：

- (IBAction)testOut:(UIButton *)sender
{
    if(![self connectedToNetwork])
    {
        UIAlertView *alert=[[UIAlertView alloc] initWithTitle:@"溫馨提示" message:@"網絡連接失敗,請查看網絡是否連接正常！" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];
        [alert release];
    }

    NSLog(@"testOut Event");
}

加入對應的頭文件：

#import <Foundation/Foundation.h>
#import <CommonCrypto/CommonHMAC.h>
#import <SystemConfiguration/SystemConfiguration.h>
#import <netdb.h>
#import <arpa/inet.h>