Question

I’m getting a semantic warning on Xcode 4 :
*Declaration of ‘struct sockaddr_in’ will not be visible outside of this function*
the struct seems to be declared in netinet/in.h

The warning is getting marked on Reachability.h, its a class that I downloaded from Apple examples.

#import <Foundation/Foundation.h>
#import <SystemConfiguration/SystemConfiguration.h>

typedef enum {
    NotReachable = 0,
    ReachableViaWiFi,
    ReachableViaWWAN
} NetworkStatus;
#define kReachabilityChangedNotification @"kNetworkReachabilityChangedNotification"

@interface Reachability: NSObject
{
    BOOL localWiFiRef;
    SCNetworkReachabilityRef reachabilityRef;
}

//reachabilityWithHostName- Use to check the reachability of a particular host name. 
+ (Reachability*) reachabilityWithHostName: (NSString*) hostName;

//reachabilityWithAddress- Use to check the reachability of a particular IP address. 
+ (Reachability*) reachabilityWithAddress: (const struct sockaddr_in*) hostAddress;

//reachabilityForInternetConnection- checks whether the default route is available.  
//  Should be used by applications that do not connect to a particular host
+ (Reachability*) reachabilityForInternetConnection;

//reachabilityForLocalWiFi- checks whether a local wifi connection is available.
+ (Reachability*) 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

I don’t understand the warning, can someone explain it to me?
Thank you.

Answer 1

Someone filed a bug report against the behavior and got a response from someone here. Essentially, the problem is that you’re declaring a new struct (so far as the compiler can tell) in the parameter of the method, so it will not be accessible elsewhere.

There is a quick fix for it. Simply add the following line to Reachability.h:

#import <netinet/in.h>