UIAlertView within mapViewDidFailLoadingMap:withError: - ios

Question

I will improve my iOS Programm by handling errors for loading a MapView. If there is no internet connection I will display an alert. But the the method mapViewDidFailLoadingMap will get called again and again so the UIAlert.
How can I achieve that the the Alert will only showed once?
- (void)mapViewDidFailLoadingMap:(MKMapView *)mapView withError:(NSError *)error {
NSString *domain = [error domain];
NSInteger code = [error code];
NSLog(#"userInfo: %#", [error userInfo]);
NSLog(#"localizedDescription: %#", [error localizedDescription]);
NSLog(#"localizedFailureReason: %#", [error localizedFailureReason]);
NSLog(#"localizedRecoverySuggestion: %#", [error localizedRecoverySuggestion]);
NSLog(#"localizedRecoveryOptions: %#", [[error localizedRecoveryOptions] description]);
if ([domain isEqualToString:NSURLErrorDomain]) {
if (code == NSURLErrorNotConnectedToInternet) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Map Loading Error" message:[error localizedDescription] delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil, nil];
[alert show];
[alert release];
}
}
}

Answer 1

If your program logic allows then you can set the delegate for the MKMapView object to nil when the failure/error occurs and it will stop sending failure/error messages to the delegate thereby preventing display of multiple alerts.
You can set delegate to nil within mapViewDidFailLoadingMap:withError method.

Answer 2

You can use a BOOL flag to ensure that the error is shown only once for the MKMapView:
- (void)mapViewDidFailLoadingMap:(MKMapView *)mapView withError:(NSError *)error
{
if (displayErrors) {
// display the error...
displayErrors = NO;
}
}
If you reset the flag in viewWillAppear for the corresponding view controller, the error will be shown once for every time the view is accessed:
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
displayErrors = YES;
}