Question

I have following code:

+ (NSDictionary*) JSONRequest: (NSString*)query andWithCredentials:(BOOL)withCredentials
{
if (withCredentials)
{
    NSString *username = [LoginHandler GetUsernameFromNSDefaults];
    NSString *password = [LoginHandler GetPasswordFromNSDefaults];
    NSString *additionalQuery = [NSString stringWithFormat:@"login_username=%@&login_password=%@", username, password];

    query = [NSString stringWithFormat:@"%@&%@", query, additionalQuery];

    [username release];
    [password release];
    [additionalQuery release]; 
}

NSURLRequest *request = [NSURLRequest requestWithURL:  
                         [NSURL URLWithString:query]];  

NSData *response = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];

NSString *jsonString = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];
NSDictionary *results = [jsonString JSONValue];
return results;

[request release];
[response release];
[jsonString release];
[results release];

}

The problem is the Release of the additionalQuery-NSString.
When I run this code, it ends with an BAD-ACCES-EXCEPTION for the

[additionalQuery release];

As soon as I comment this out, the code works fine.

Now, as simple as it is, run my app without this line of code could be fine, but my question is: What do Im wrong?

I generate an NSString in an IF-Clause, then I CAN only release it in the IF-Clause. But why I got a Error there?

Answer 1

Look at your creation of additionalQuery

NSString *additionalQuery = [NSString stringWithFormat:@"login_username=%@&login_password=%@", username, password];

With stringWithFormat you create an autoreleased NSString object. You MUST NOT release it manually according to the Memory Management rules since you don’t own it.

You own only things you created with alloc] init..] or something with new.. or create.. in the name and of course if you do a copy such as mutableCopy.

So [additionalQuery release] causes over-releasing an object and thus it is a BAD ACCESS