regarding potential leak - iphone

Question

am getting the potential leak in the following code.(returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];)pls help me to find out.
+ (NSString *) getResponseFromServer:(NSString *) url
{
NSString *URLString1 = [NSString stringWithContentsOfURL:[NSURL URLWithString:#"http://www.google.com"]];
if(URLString1 == NULL)
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Info" message:#"You must be connected to the Internet to use this app. Wireless , 3G and EDGE are supported" delegate:self cancelButtonTitle:#"OK" otherButtonTitles:nil];
alert.delegate = self;
[alert show];
[alert release];
return #"NO" ;
}
else
{
//CFStringRef escapeChars = (CFStringRef) #":/?#[]#!$&’()*+,;=";
// url = (NSString *) CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)url, NULL, escapeChars, kCFStringEncodingUTF8);
url = [url stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding];
//[self alert:escapedUrlString];
url=[url stringByReplacingOccurrencesOfString:#"%2526" withString:#"%26"];
//NSLog(#"url 2 = %# ",url);
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setURL:[NSURL URLWithString:url]];
NSLog(#"******Loading URL = %#",[NSURL URLWithString:url]);
NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSString *returnString = #"";
if(returnData)
{
returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding]; //Potential leak here...
// NSRange range = [str rangeOfString:supplierSearchText.text options:NSCaseInsensitiveSearch];
//NSLog(#"Searching = %d, %#, %#, %d", i, str, supplierSearchText.text, range.location);
//if(range.location == 0)
int num = [url rangeOfString:#"iphone_logout.php" options:NSCaseInsensitiveSearch].location;
NSLog(#">>>>>>>>> NUmber = %d", num);
if(isUserLoggedIn > 0 && global_Timer != nil && num > 1000)
{
if(((int)([url rangeOfString:#"iphone_user.php" options:NSCaseInsensitiveSearch].location) < 1000) ||
((int)([url rangeOfString:#"company_name.php" options:NSCaseInsensitiveSearch].location) < 1000) ||
((int)([url rangeOfString:#"company_search.php" options:NSCaseInsensitiveSearch].location) < 1000) ||
((int)([url rangeOfString:#"view_web.php" options:NSCaseInsensitiveSearch].location) < 1000))
{
[global_Timer invalidate];
NSLog(#">>>>>>>> Timer invalidating >>>>>>>>>>>>>>, %d, %d, %d, %d", ((int)([url rangeOfString:#"iphone_user.php" options:NSCaseInsensitiveSearch].location) > -1) , ((int)([url rangeOfString:#"company_name.php" options:NSCaseInsensitiveSearch].location) > -1) , ((int)([url rangeOfString:#"company_search.php" options:NSCaseInsensitiveSearch].location) > -1), ((int)([url rangeOfString:#"view_web.php" options:NSCaseInsensitiveSearch].location) > -1) );
global_Timer = [NSTimer scheduledTimerWithTimeInterval:(NSTimeInterval)300.0 target:global_SupplierToolsViewController selector:#selector(pressButton_Logout) userInfo:nil repeats:NO];
}
else {
NSLog(#"No matches found!, %d", (int)([url rangeOfString:#"iphone_user.php" options:NSCaseInsensitiveSearch].location));
}
}
}
else //if(!networkFlag)
{
//networkFlag = YES;
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:#"Network connection failed! Try again later!" delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alert show];
[alert release];
return #"NO";
}
//[url release];
[request release];
return returnString;
}
}

Answer 1

You could add autorelease to the creation of the string.
In general, any time you use alloc you need to either use autorelease or else use release.

Answer 2

You have a path that returns before releasing the request.
else //if(!networkFlag)
{
//networkFlag = YES;
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:#"Network connection failed! Try again later!" delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alert show];
[alert release];
return #"NO";
}
//[url release];
[request release];

Answer 3

You are alloc-ing returnString without a matching release.
Try having an autoreleased string, like so:
returnString = [NSString stringWithData:returnData encoding:NSUTF8StringEncoding];