使用NSXMLParser时发生内存泄漏

Question

我在以下代码中处理内存泄漏时遇到一些困难。

使用XCode中的泄漏工具，该工具显示了我用于rss解析的某些代码中的内存泄漏。

我正在使用XCode 4，并在代码底部释放分配。 我尝试将发布添加到每个导致崩溃或程序停止工作的本地部分。

任何意见的帮助，不胜感激！

导致泄漏的代码：

- (void)parser:(NSXMLParser *)parser parseErrorOccurred:(NSError *)parseError {
NSString * errorString = [NSString stringWithFormat:@"Unable to download story feed from web site (Error code %i )", [parseError code]];
UIAlertView * errorAlert = [[UIAlertView alloc] initWithTitle:@"Error loading content" message:errorString delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
[errorAlert show];
}

- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict {
currentElement = [elementName copy];
if ([elementName isEqualToString:@"item"]) {
item = [[NSMutableDictionary alloc] init];
currentImage = [[NSMutableString alloc] init];
currentTitle = [[NSMutableString alloc] init];
currentDate = [[NSMutableString alloc] init];
currentSummary = [[NSMutableString alloc] init];
currentLink = [[NSMutableString alloc] init];
}
}

- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName {
if ([elementName isEqualToString:@"item"]) {
[item setObject:currentImage forKey:@"media"];
[item setObject:currentTitle forKey:@"title"];
[item setObject:currentLink forKey:@"link"];
[item setObject:currentSummary forKey:@"summary"];
[item setObject:currentDate forKey:@"date"];
[stories addObject:[item copy]];
}
}

- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string {
if ([currentElement isEqualToString:@"media"]) {
[currentImage appendString:string];
} else if ([currentElement isEqualToString:@"title"]) {
[currentTitle appendString:string];
} else if ([currentElement isEqualToString:@"link"]) {
[currentLink appendString:string];
} else if ([currentElement isEqualToString:@"description"]) {
[currentSummary appendString:string];
} else if ([currentElement isEqualToString:@"pubDate"]) {
[currentDate appendString:string];
}
}

然后发布：

- (void)dealloc {
[currentElement release];
[rssParser release];
[stories release];
[item release];
[currentImage release];
[currentTitle release];
[currentDate release];
[currentSummary release];
[currentLink release];
[super dealloc];
}

Answer 1

更改以下内容：

UIAlertView * errorAlert = [[[UIAlertView alloc] initWithTitle:@"Error loading content" message:errorString delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil] autorelease];

此代码仅应执行一次：

item = [[NSMutableDictionary alloc] init];
currentImage = [[NSMutableString alloc] init];
currentTitle = [[NSMutableString alloc] init];
currentDate = [[NSMutableString alloc] init];
currentSummary = [[NSMutableString alloc] init];
currentLink = [[NSMutableString alloc] init];

Answer 2

在每个didStartElement:方法的开始处，都会创建新实例，但在取消分配类时仅释放一次。 因此，就像didStartElement:调用didStartElement:一样，存在字符串对象实例的构建。

您可能想要的是在类的实例中创建一次这些实例，然后在遇到元素时将其追加到实例中。

无论如何，为每个分配发布。