Now it's time for me to ask a question. Until now I just ignored that Memory Leak. But now it's to find out which object leads to this leak.
I have the following code:
NSDictionary *addressDic = [[NSDictionary alloc] initWithDictionary:[NSPropertyListSerialization propertyListFromData:plistData mutabilityOption:NSPropertyListImmutable format:&format errorDescription:&anError]];
At a later Point I also release the addressDic.
If I use Instruments to detect Memory Leaks I get one at above posted code. I'm leaking about 16 Bytes and the objecttype is NSCFString. Why?
I hope you can help me.
Sandro
You need to -release the anError variable if there is an error.
Related
In my application, I am not able to remove the following memory leaks:
[NSCFString appendString]
[NSCFString copyWithZone];
[NSDecimalNumberPlaceHolder initWithDecimal]
[SBJsonParser scanRestOfArray]
[SBJsonParser scanRestOfDictionary]
[NSPlaceholderMutableString initWithCapacity]
How to remove these leaks?
These are not leaks caused by system libraries. Leaks tool just points you where is the possible cause of the leak. For example, if you write like this:
NSString* str = [[NSString alloc] initWithCString: "some_str"];
In this example str is allocated but never released. Leaks tool would show you that there is a leak in [NSPlaceholderString initWithCString:] but in fact there is leak because you didn't send release message to str.
So a little tip: always search problem in your own code and not in the frameworks you're using.
NSString *anError = nil;
id plist;
plist = [NSPropertyListSerialization propertyListFromData:rawCourseArray mutabilityOption:NSPropertyListImmutable format:&format errorDescription:&anError];
if (anError != nil){
[anError release];
}
The above code causes a memory leak every time I call it. I am releasing the error but still there is a leak. I haven't seen any resolution to this issue. I posted this already and most respond that this is not a leak. But see here in the leak performance tool:
I need this fixed because eventually my app crashes. Any ideas? Many thanks
I had the same problem. Used propertyListWithData:options:format:error: with same result. Used NSDictionary initWithContentsOfFile with same result:
Leaked Object # Address Size Responsible Library Responsible Frame
NSCFNumber,19 < multiple > 304 Bytes MediaToolbox FigRemote_CreatePropertyListFromBinaryPListData
FWIW - I only have dictionaries and arrays and strings in the pList, no numbers.
The issue is not the error object (or string in your method). The issue is not plist above, since it should be autorelease. In the end, I gave up and reimplemented using JSON and:
http://stig.github.com/json-framework/api/index.html
==> no more leak.
Best,
Fred
I've had the same problem before.
Basically this is because your error variable got released without initiating it. So what you can do is try to init your NSString *error to an empty string before releasing it. Or not releasing it at all.
I have the following piece of code and when I use Instruments/Object Allocations, it tells me that there is a leak there (which goes down to sqlite3MemMalloc). Is there something that I should release?
if (![managedObjectContext save:&error]) {
NSLog(#"Error while saving.");
}
The save works well and doesn't trigger an error.
The leak is most likely in one of the managed objects being saved and it just shows here. If you look at the stack in Instruments you can probably see the leaking object. Since it only shows up at save, it's probably in validation code.
Do you have any subclasses of your NSManagedObject instances?
When you set a value into your NSManagedObject instances do you then release your ownership of them? For example if you were do to the following code:
NSString *someString = [[NSString alloc] initWithString:#"Blah"];
[myManagedObject setValue:someString forKey:#"stringValue"];
You would be leaking memory because you are still owning that NSString. That is what TechZen is referring to above.
Would it shed more light if I told that fetchHTML was being called in a seperate thread? I am also seeing several messages in the debug console such as:
_NSAutoreleaseNoPool(): Object 0xd92860 of class NSCFDictionary autoreleased with no pool in place - just leaking
_NSAutoreleaseNoPool(): Object 0xd92800 of class NSCFString autoreleased with no pool in place - just leaking
I am new to iPhone app development, Objective-C but not new to programming or C/C++. I am using the leaks performance tool and it shows many leaks. This is a 10.5 kb leak and it occurs on the line:
NSString * xml = [NSString stringWithContentsOfURL:urlobj];
The stack trace on this below is:
stringWithContentsOfURL
initWithContentsOfURL
initWithDataOfEncoding
...
Does anyone have an idea why this must be happening. I am under the impression that I get an autorelease object here and I can return this to the caller without calling retain. I am not using the xml object to store in an instance variable, just for processing.
Here is the function code:
- (NSString *) fetchHTML: (NSString* ) url{
#try
{
NSURL* urlobj = [NSURL URLWithString:url];
NSString * xml = [NSString stringWithContentsOfURL:urlobj];
return xml;
}
#catch( NSException *ex){
NSLog(#"Error fetchingHTML");
return nil;
}
return nil;
}
Yup; that shouldn't be leaking.
It might be a false positive in that the URL subsystem is caching the contents of the URL and doing so in a way where the pointer is no longer visible to leaks analysis.
If you can, retry the test on Snow Leopard. Leaks detection on Snow Leopard is significantly faster and more accurate.
I completely agree with you that this should not cause a leak. I've been coding in Cocoa/Objective-C for 2 years now, and that looks like it should work.
That being said, I notice that Apple's documentation indicates that the stringWithContentsOfURL: method is being deprecated. Perhaps it would work as follows:
NSString * xml = [[NSString alloc]
initWithContentsOfURL:urlobj
encoding:NSASCIIStringEncoding
error:nil];
return [xml autorelease];
As the error message says, there's no autorelease pool for the string to go into, and that creates a leak. NSAutoreleasePools exist on a per-thread basis. Cocoa creates one in the main event loop of the main thread, but that's the only one it creates for you. If you're somewhere other than the main thread and you're going to be dealing with autoreleased objects, you need to create an autorelease pool for that thread as well.
You can check out the NSAutoreleasePool docs for more information on how autorelease pool stacks work.
I am simply loading a plist into a temporary dictionary for initializing my data model. Unfortunately this single line of code below results in consistent leak throughout the app life cycle as per Instruments. The leaked objects being NSCFString and GeneralBlock on a Malloc and the responsible library being Foundations.
My two questions for the experienced eyes:
Am I doing something strange to trigger this ? I tried surrounding it in autorelease block but it had no effect.
Is there a way to print list of object references of a suspect object to get insight into the object orphaning process.
Leaking Line:
NSDictionary *tempDict = [NSDictionary dictionaryWithContentsOfFile:
[[NSBundle mainBundle]
pathForResource:resourceName
ofType:#"plist"]];
totalChapters = [[tempDict objectForKey:#"NumberOfChapters"] intValue];
chapterList = [[NSMutableArray alloc] initWithCapacity: totalChapters];
[chapterList addObjectsFromArray:[tempDict objectForKey:#"Chapters"]];
It appears you may be leaking at this line:
[[NSMutableArray alloc] initWithCapacity: totalChapters];
If that object isn't being released, then any objects you add to it won't be released either
Edit (because it's too long for a comment):
Instruments tells you where the memory was allocated, but not why it is still being retained. When NSDictionary loads the contents of a file, it has to create an object for each element it loads. If one later retrieves an object using objectForKey:, retain it and forget to release, a leak will be reported. The dictionaryWithContentsOfFile statement will be blamed for it because it performed the allocation.
I concur with Don's phantom debugging. Most likely you haven't released the old chapterList when you assign to it the second time.
I am releasing all the allocated stuff in the dealloc method of this class. The TROUBLED line below gets repeatedly called in each alloc init to help me load new chapters based on user selection.
NSDictionary *tempDict = [NSDictionary dictionaryWithContentsOfFile:[[NSBundle mainBundle] pathForResource:resourceName ofType:#"plist"]];
Since I am using convenience method on NSDictionary I don't have anything to Dealloc. But Instrument points to this particular line as the source of leak via a Malloc.
tempDict is a just a scratch space for a dictionary to load a plist and init the ivars.
The autorelease block only effects objects placed into the autorelease pool. So tempDict is place in the autorelease pool but totalChapters is not. If you would like to use the autorelease pool then you either want:
[[[NSMutableArray alloc] initWithCapacity: totalChapters] autorelease];
or don't use the autorelease pool and use:
[[NSMutableArray alloc] initWithCapacity: totalChapters]
and then
[totalChapters release]
Avoiding the autorelease pool is recommended unless necessary.