A work around to the memory leaks in NSXMLParser
Posted by Filip Ekberg on November 30 2010 7 Comments
Posted by Filip Ekberg on November 30 2010 7 Comments
Lately I’ve experimenting a bit with parsing XML in Objective-C and discovered something that I’d like to share with you all.
First of all, consider the following “standard” way of downloading an XML and parsing it
initWithContentsOfURL: [NSURL
URLWithString:@"http://some-xml-url.com/my.xml"]];
You would think that this line of code is Solid, all it’s supposed to do is download the content, release the temporary resources for fetching data and store the final content for the parsing later on. However somewhere in the process there’s a resource that isn’t cleaned up properly and you will get a memory warning the “Build and Analyze” method wont find it but when you run the application with a Performance tool looking for leaks you will end up getting something like this:
Leaked Object
Malloc 512 Bytes
Responsible Frame
allocateCollectableUnscannedStorage
Leaked Object
NSConcreteMapTable
Responsible Frame
+[NSMapTable alloc]
I tried a lot of suggestions to fix this issue some of them being to set the sharedURLCache to 0 like this:
These alone did not solve the problem, so on the quest to find a proper work around I came up with this solution:
[[NSURLCache sharedURLCache] setDiskCapacity:0];
NSData *xml = [NSData
dataWithContentsOfURL: [NSURL
URLWithString:@"http://some-xml-url.com/my.xml"]];
NSXMLParser *parser = [[NSXMLParser alloc] initWithData:xml];;
And that did it, after this I no longer received any memory warnings.
Filip Ekberg is a Senior Software Engineer working in the country with all the polar bears, author of a self-published C# programming book and overall in love with programming.
Thank you.. my problem is solved..
Wow that actually makes a difference, initing it with contents of URL or data!
Tnx it Works!!!
Thanks that really works!
One clue it also works without:
[[NSURLCache sharedURLCache] setMemoryCapacity:0];
[[NSURLCache sharedURLCache] setDiskCapacity:0];
It might be that problem is inside initializing NSXMLParser with URL.
Filip,
Thanks for posting this. Not sure how I would have been able to fix these leaks other wise. Your my new best friend!
Bill
Thanks for this, you just saved my day
TACK! Två veckor förlorade jag på att försöka täta denna läckan. Sedan hittade jag din post.