what cause error NSNetServicesErrorCode = "-72000"? - ipad

Question

i create a simple browser that can load a local file using UIWebview. At first,when i try to preview a html file, the uiwebview can load the source file and preview it. But after i minimize the app (the app enter background), and then open the app again, i've got this error :
Error Dict: {
NSNetServicesErrorCode = "-72000";
NSNetServicesErrorDomain = 10;
}
and after that, the uiwebview can not load the source file, when i log the error in (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error, it shows this message :
Error Domain=NSURLErrorDomain Code=-1004 "Could not connect to the server." UserInfo=0x53d610 {NSErrorFailingURLStringKey=http://localhost:9898/local/a.html?83C66B33-874C-41A7-BBF5-78D1615512DF, NSErrorFailingURLKey=http://localhost:9898/local/a.html?83C66B33-874C-41A7-BBF5-78D1615512DF, NSLocalizedDescription=Could not connect to the server., NSUnderlyingError=0x5ccaa0 "Could not connect to the server."}
the app isn't crash, but the spinning indicator is never stop.
could somebody tell me what cause this case? and how to solved it?
Thank you :)

Answer 1

If you look inside the NSNetServices header, you'll see the following enum that explains each error:
typedef NS_ENUM(NSInteger, NSNetServicesError) {
/* An unknown error occured during resolution or publication.
*/
NSNetServicesUnknownError = -72000L,
/* An NSNetService with the same domain, type and name was already present when the publication request was made.
*/
NSNetServicesCollisionError = -72001L,
/* The NSNetService was not found when a resolution request was made.
*/
NSNetServicesNotFoundError = -72002L,
/* A publication or resolution request was sent to an NSNetService instance which was already published or a search request was made of an NSNetServiceBrowser instance which was already searching.
*/
NSNetServicesActivityInProgress = -72003L,
/* An required argument was not provided when initializing the NSNetService instance.
*/
NSNetServicesBadArgumentError = -72004L,
/* The operation being performed by the NSNetService or NSNetServiceBrowser instance was cancelled.
*/
NSNetServicesCancelledError = -72005L,
/* An invalid argument was provided when initializing the NSNetService instance or starting a search with an NSNetServiceBrowser instance.
*/
NSNetServicesInvalidError = -72006L,
/* Resolution of an NSNetService instance failed because the timeout was reached.
*/
NSNetServicesTimeoutError = -72007L,
};
You're getting a service collision error, which means that a net service with the same domain, type, and name are already publishing their service on your network.
In general, I always consult the header file for error codes. They're nearly always assigned by an enum value, and the enum usually has a much more descriptive name than the number used.

Answer 2

The problem seems to be the host you are trying to connect to: http://localhost:9898/local/[..]
Localhost on your computer is your computer, localhost on your ipad is your ipad - for testing use resolvable domain name or ip address.

Answer 3

Sergiu Todirascu's comment in the question solved it for me. The Mac Sandbox was causing this, I had to turn on Networking, in my case Incoming and Outgoing network checkboxes, in the entitlements tab. Creating an answer so it is more easy to see.