内存泄漏的NSMutableString appendString [英] Memory Leak with NSMutableString appendString

问题描述

我使用的是XMLParser的解析一些XML数据，它使用一个的NSMutableString * resultString存储标记字符。在每一个（ - 解析器：didStarElement ...）方法我分配和初始化的resultString-伊娃

I am using an XMLParser to parse some XML data, which uses an NSMutableString *resultString to store the tag characters. At every (- parser: didStarElement...) method I allocate and init the resultString-ivar.

-  (void)parser: (NSXMLParser *)parser didStartElement: (NSString *)elementName namespaceURI: (NSString *)namespaceURI qualifiedName: (NSString *)qName attributes: (NSDictionary *)attributeDict { 
// Alot of if-statements to sort subtags
// /.../
    resultString = [[NSMutableString alloc] init];
    recordResults = YES;
}

foundCharacters法：

该字符串在解析器追加。我读的地方，自动释放的对象，如内appendString字符串可能会导致内存泄漏的形象。所以我加了一个本地autorelease池，以确保它得到倒掉马上（不会发生任何变化虽然）：

The string is appended in the parser:foundCharacters-method. I read somewhere that autoreleased objects, like the string inside appendString could cause the image of a memory leak. So i added a local autorelease pool to make sure it got drained right away (no change in behavior though):

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
if(recordResults) {
    [resultString appendString: string];
}
[pool drain];
}

在解析器：didEndElement ...我终于释放和无出resultsString：

In the parser:didEndElement... I finally release and nil out the resultsString:

-(void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {

   // Alot of if statements to handle differnt tags
   // each of which has the structure of the last else-statement
   // In other words, I am pretty sure I've covered every possible
   // case to prevent the resultString from
   // not getting released and niled out
    if(...) {
            ...
}
    else if(...) {
            ...
    }
else {
    if(resultString != nil) {
        [dataDict setObject: resultString forKey: elementName];
        [resultString release];
        resultString = nil;
    }
}

仪器检漏工具标志解析器：foundCharacter法作为内存泄漏的来源，所以我不知道这是由appendString造成的。或者，如果你能找到这个code是出路错误的东西。
这是一个相当内存渴求应用，解析在iPhone上不少，有时适度的大XML的文件，所以我的问题是如何找到一个变通，如果的NSMutableString appendString是不是在这种情况下，适当的...

Instruments Leak-tool flags the parser:foundCharacter-method as a source for memory leakage, so I wonder if this is caused by appendString. Or if you can find something in this code that is way out wrong. This is a rather memory craving application, parsing quite a few and sometimes moderately big XML-files on an iPhone, so my question would be how to find a work around, if the NSMutableString appendString is not appropriate in this case...

在此先感谢！

推荐答案

如果结束标记丢失，你将有一个内存泄漏。最好是有parserDidStartDocument任何分配：在parserDidEndDocument和释放：，因为这些都是保证配对。而不是在didStartElement分配resultString，你只是截断它。

If an end tag is missing, you will have a memory leak. It is better to have any allocations in parserDidStartDocument: and deallocations in parserDidEndDocument:, as these are guaranteed to be paired. And instead of allocating resultString in didStartElement, you just truncate it there.

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