Please Explain How This Could Be Leaking - String Encoding Function
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i got a report from my analyser that this function could potentially be leaking. Can anyone shed any light as to why?

    - (NSString *)encodeString:(NSString *)string {
    	
    	NSString *newString = NSMakeCollectable([(NSString *)CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)string, NULL, CFSTR(":/?#[]@!$ &'()*+,;=\"<>%{}|\\^~`"), CFStringConvertNSStringEncodingToEncoding(NSUTF8StringEncoding)) autorelease]);
        
    	return newString;
    	
    }