NSURLErrorDomain error code -999 in iOS

The error has been documented on the Mac Developer Library(iOS docs)

The concerned segment from the documentation will be:

URL Loading System Error Codes

These values are returned as the error code property of an NSError object with the domain “NSURLErrorDomain”.

enum
{
   NSURLErrorUnknown = -1,
   NSURLErrorCancelled = -999,
   NSURLErrorBadURL = -1000,
   NSURLErrorTimedOut = -1001,

As you can see; -999 is caused by ErrorCancelled. This means: another request is made before the previous request is completed.

hjpotter92 is absolutely right, I just want to provide solution for my case. Hopefully it is useful for you as well. Here is my situation:

On log in page > press log in > pop up loading dialog > call log in service > dismiss dialog > push another screen > call another service --> cause error -999

To fix it, I put a delay between dismissing dialog and pushing new screen:

    [indicatorAlert dismissWithClickedButtonIndex:0 animated:YES];
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 0.01 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
                [self performSegueWithIdentifier:@"HomeSegue" sender:nil];
            });

It is strange that this issue happens on iOS 7 only.

Just wanted to add here, when receiving a -999 "cancelled" the problem usually is one of two things:

• You're executing the exact same request again.
• You're maintaining a weak reference to your manager object that gets deallocated prematurely. (Create strong reference)