AFNetworking fail with response.statusCode 0 - ios

Question

I want to get address from latitude and longitude with GoogleGEO CODING (EX URL = http://maps.googleapis.com/maps/api/geocode/json?latlng=40.714224,-73.961452&sensor=true_or_false )
So I want to get JSON from that page by AFNetworking.
It's my code below :
IBAction)reLocation:(UIButton*)sender
{
if(sender.tag==1)
{
NSArray *gpsValue = [self getGPS];
float lat = [[gpsValue objectAtIndex:0] floatValue];
float lon = [[gpsValue objectAtIndex:1] floatValue];
NSString *string = [NSString stringWithFormat:#"%#%#,%#&sensor=true_or_false",GEOCODING_URL,[NSString stringWithFormat:#"%f", lat],[NSString stringWithFormat:#"%f",lon]]; // NSString *str = [NSString stringWithFormat:#"%f", myFloat];
NSLog(string);
NSURL *url = [NSURL URLWithString:string];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];
operation.responseSerializer = [AFJSONResponseSerializer serializer];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject)
{
NSLog(#"AFNetworking success");
NSDictionary *location = (NSDictionary *)responseObject;
// 3
self.title = #"JSON Retrieved";
//[self.tableView reloadData];
NSLog(responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"AFNetworking failure");
switch (operation.response.statusCode) {
case 400:
// Do stuff
NSLog(#"error 400");
break;
default:
NSLog([NSString stringWithFormat:#"%ld",(long)operation.response.statusCode]);
break;
}
// 4
UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:#"Error Retrieving Weather"
message:[error localizedDescription]
delegate:nil
cancelButtonTitle:#"Ok"
otherButtonTitles:nil];
[alertView show];
}];
// 5
[operation start];
}}
But when I click my button, always afnetworking fails and log shows 0 for status code.
I also got url log that i put in
i already checked that url is not problem (it shows json in working order)
I debug with simulator!
Is there something I miss ?