Leaks in passing the request using URL at NSString, Objective-C - objective-c

Question

I getting the leak in this method even the allocated nsstring is released.
Now I am taken stringWithFormat, but still it is showing the leak at "NSData *returnData=...." line
-(BOOL)getTicket:(NSString*)userName passWord:(NSString*)aPassword isLogin:(BOOL)isLogin
{
NSString* str=#"";
if (isLogin == YES)
{
str =[NSString stringWithFormat:#"AGENT=true&LOGIN_ID=%#&PASSWORD=%#",[self _encodeString:userName],[self _encodeString:aPassword]];
}
else if (isLogin == NO)
{
str =[NSString stringWithFormat:#"AGENT=true&LOGIN_ID=%#&PASSWORD=%#",[self _encodeString:userName],[self _encodeString:aPassword]];
}
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:str]
cachePolicy:NSURLRequestReloadIgnoringCacheData
timeoutInterval:25.0];
[request setHTTPMethod: #"POST"];
NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];
printf("\n returnString in getticket:%s",[returnString UTF8String]);
NSRange textRange;
textRange =[returnString rangeOfString:#"TICKET"];
if(textRange.location != NSNotFound)
{
NSArray* splitValues = [returnString componentsSeparatedByString:#"TICKET="];
NSString* str1 = [splitValues objectAtIndex:1];
NSArray* splitValues1 = [str1 componentsSeparatedByString:#"RESULT"];
NSString* ticket1 = [splitValues1 objectAtIndex:0];
self.ticket = ticket1;
self.isCorrectLogin = YES;
[returnString release];
return YES;
}
else
{
self.isCorrectLogin = NO;
[returnString release];
return NO;
}
return NO;
}
Please help me out of this problem.

Answer 1

Macbirdie is correct in that composing a string using stringByAppendingString: is horribly inefficient. I would suggest using +stringWithFormat: instead.
As for the leak, if the leak is where you say it is, then it might be a leak in the underlying framework (and it might be a false positive). Post the backtrace of the leaked object (which can be had from the Allocations instrument).