I'm testing my Objective C project for memory leaks using xCode Instruments tool.
The following lines (in my procedure to find matches in Game Center) are generating a Memory Leak:
GKMatchRequest *request = [[GKMatchRequest alloc] init];
request.minPlayers = minPlayers;
request.maxPlayers = maxPlayers;
GKMatchmakerViewController *mmvc = [[GKMatchmakerViewController alloc] initWithMatchRequest:request];
According to the Instruments Stack Trace, the Leaked Object is "GKMatchRequest".
Responsible Library: GameCenterFoundation
Responsible Frame: -[GKMatchRequest copyWithZone:]
I'm using ARC, so it should not be required to include 'Autorelease' right after the 'request' as suggested in some forums reporting a similar issue (i.e.: https://forums.coronalabs.com/topic/59315-ios-native-plugin-objective-c-memory-leak/).
How to avoid this memory leak in my code ?
Related
HarrisAnnotation *harrisAnnotation = [[HarrisAnnotation alloc] init];
[self.mapAnnotations insertObject:harrisAnnotation atIndex:0];
[harrisAnnotation release];
Running analyze on project show
Potential leak of an object
for
harrisAnnotation
Never mind, I'm not used to using Xcode. It was the line below.
I'm using the profiler in xcode 4 to determinate if I have any memory leaks. I didn't have this leak before, but with xcode 5 I have this one.
I'm trying to set an image for the tab item of my `UIViewController and the profiler marks this line :
image = [[UIImage alloc] initWithContentsOfFile:imgPath]; <<=== Leak : 9.1%
This is part of my code I don't understand why. What's the best way to resolve this issue?
NSString *imgPath;
UIImage *image;
IBNewsViewController *newsView = [[IBNewsViewController alloc] initWithURL:[tvLocal urlFlux] title:#"News" isEmission:NO];
[newsView setTitle:#"News"];
imgPath = [[NSBundle mainBundle] pathForResource:"news" ofType:#"png"];
image = [[UIImage alloc] initWithContentsOfFile:imgPath]; <<=== Leak : 9.1%
newsView.tabBarItem.image = image;
[image release];
image = nil;
UINavigationController* navNew = [[UINavigationController alloc] initWithRootViewController:newsView];
[newsView release];
newsView = nil;
EDIT:
No leak on iOS6.
Why it's leak on iOS7?
You should switch to the autoreleasing imageNamed: method. This has the added benefit of system level cacheing of the image.
NSString *imgPath;
UIImage *image;
IBNewsViewController *newsView = [[IBNewsViewController alloc] initWithURL:[tvLocal urlFlux] title:#"News" isEmission:NO];
[newsView setTitle:#"News"];
image = [UIImage imageNamed: #"news"];
newsView.tabBarItem.image = image;
UINavigationController* navNew = [[UINavigationController alloc] initWithRootViewController:newsView];
[newsView release];
newsView = nil;
To make life easier on yourself I'd switch your project to use ARC so you have less to worry about WRT memory management.
Replace this line
image = [[UIImage alloc] initWithContentsOfFile:imgPath];
With
image = [UIImage imageWithContentsOfFile:imgPath];
and check once.
First, switch to ARC. There is no single thing you can do on iOS that will more improve your code and remove whole classes of memory problems with a single move.
Beyond that, the code above does not appear to have a leak itself. That suggests that the actual mistake is elsewhere. There are several ways this could happen:
You're leaking the IBNewsViewController somewhere else
IBNewsViewController messes with its tabBarItem incorrectly and leaks that
You're leaking the UINavigationController somewhere else
You're retaining the tabBarItem.image somewhere else and failing to release it
Those are the most likely that I would hunt for. If you're directly accessing ivars, that can often cause these kinds of mistakes. You should use accessors everywhere except in init and dealloc. (This is true in ARC, but is absolutely critical without ARC.)
Leak detection is not perfect. There are all kinds of "abandoned" memory that may not appear to be a leak. I often recommend using Heapshot (now "Generation") analysis to see what other objects may be abandoned; that may give you a better insight into this leak.
Why differences in iOS 6 vs iOS 7? I suspect you have the same problem on iOS 6, but it doesn't look like a "leak", possibly because there is something caching the image that was removed in iOS 7. The cache pointer may make it look like it's not a leak to Instruments.
Speaking of which, do make sure to run the static analyzer. It can help you find problems.
And of course, switch to ARC.
I have been tracking down memory leaks in my iOS app and I keep coming back to the following code using the leaks instrument:
NSMutableArray *resultSet = [[NSMutableArray alloc] initWithCapacity:3];
NSAutoreleasePool *innerPool = [[NSAutoreleasePool alloc] init];
FMResultSet *rs = [db executeQuery:query,equipmentID];
while ([rs next])
{
[resultSet addObject: [rs resultDict]];
}
[rs close];
[innerPool release];
return [resultSet autorelease];
Is this the correct (in terms of memory management) usage of FMDB? Here is a screenshot of the leaks instrument:
leaks
Detailed Screenshot of the leak:
detail
Yes, this is correct memory management. The [rs close]; line is technically unnecessary, because it will happen (if it hasn't already) when the FMResultSet is deallocated (as part of the pool draining). But putting it in there explicitly is fine.
Is it possible you're over-retaining the return array?
SQLite allocates and keeps a bunch of memory, which is only freed when the database is closed. You can also adjust how much memory it will allocate by issuing a 'pragma cache_size = nnn' command.
See this related question and answer:
memory leak (?) after sqlite+fmdb vacuum command
I have a memory leak in my iPhone app. I added Google AdMob to my app using sample code downloaded from Google. However, I was having a hard time getting it into testing mode so I added an extra variable as follows:
GADRequest *r = [[GADRequest alloc] init];
r.testing = YES;
[bannerView_ loadRequest:r];
I found the memory leak using Instruments. Instruments does not lead me to this line of code, it just dumps me in the main.m file. However, when I comment out the code relating to AdMob the leak goes away and I know enough to see that I haven't taken care of releasing this new variable. I just don't know exactly how I should set about releasing it. The variable r is not addressed in the header file so this is all the code that deals with it.
I tried adding:
- (void)dealloc {
[r release];
....
}
but that caused a build error saying "'r' undeclared". That's weird because it looks to me like I'm declaring r in the first quoted line above but I guess that's wrong. Any help would be much appreciated. I really have tried to educate myself about memory leaks but I still find them very confusing.
Just add [r release]; right below the code:
GADRequest *r = [[GADRequest alloc] init];
r.testing = YES;
[bannerView_ loadRequest:r];
[r release];
The variable r is declared only in that section of your code, so that's where it should be released. The point of releasing is to get rid of it as soon as you no longer need it, so the above should work perfectly for you.
If your r is locally declared (as it seems, judging from your snippet), then it cannot be accessed from outside its scope (here: the method it was declared in).
You either need to make it accessible within your class instance by declaring it an ivar.
Declaring it an ivar would look like this:
#interface YourClass : SuperClass {
GADRequest *request;
}
//...
#end
You then change your code to this:
request = [[GADRequest alloc] init];
request.testing = YES;
[bannerView_ loadRequest:request];
Also don't forget to release it in dealloc:
- (void)dealloc {
[request release];
//...
}
However this is not what you want in this situation (I've just included it to clarify why you get the warning about r not being declared).
You (most likely) won't need request any second time after your snippet has run, thus storing it in an ivar will only needlessly occupy RAM and add unwantd complexity to your class. Stuff you only need at the immediate time after its creation should be taken care of (released) accordingly, that is within the very same scope.
What you'll actually want to do is simply (auto)release it, properly taking care of it.
Keep in mind though that your loadRequest: will need to take care of retaining r for as long as it needs it. Apple's implementation does this, of course. But you might want to write a similar method on your own one day, so keep this in mind then.
GADRequest *r = [[GADRequest alloc] init];
r.testing = YES;
[bannerView_ loadRequest:r];
[r release]; //or: [r autorelease];
OP here. Thanks for all the detailed and thoughtful responses. This has definitely helped get a better handle on memory management. I did exactly as recommended, adding [r release]; right below the posted code. However, I still have a leak. I have isolated it to a single line of code. The following leaks:
GADRequest *r = [[GADRequest alloc] init];
r.testing = YES;
[bannerView_ loadRequest:r];
[r release];
The following does not leak:
GADRequest *r = [[GADRequest alloc] init];
r.testing = YES;
// [bannerView_ loadRequest:r];
[r release];
I figure I'm changing the retain count on bannerView with the loadRequest but I don't know how to fix it. I tried a [bannerView_ release] immediately after the [r release]; line (i.e. releasing locally) but that didn't work. I didn't expect it to because bannerView_ is declared elsewhere. I tried [bannerView_ release]; in the dealloc method but that didn't work. I also tried [bannerView_ autorelease]; locally. The wise heads at Google put [bannerView_ release]; in the ViewDidUnload method.
It's possible that Instruments is just messing with my head. The leak appears after about 10 seconds but the app performs well and the amount of memory leaked doesn't seem to be spirally upwards as the app continues to run. Is there such a thing as a benign memory leak?
Thanks again for your help,
Dessie.
I have an application that runs in the background only (by specifying LSBackgroundOnly in the info.plist file).
The problem is, that all blocks that I run on parallel queues are not being released.
The code is executed in a memory-managed environment - no GC is involved.
The (simplified) code looks like below. Blubber is just some dummy class that holds an NSDate for testing. Also, it overwrites retain, release, and dealloc to do some logging:
NSOperationQueue *concurrentQueue = [[NSOperationQueue alloc] init];
[concurrentQueue setMaxConcurrentOperationCount:NSOperationQueueDefaultMaxConcurrentOperationCount];
Blubber *aBlubber = [[Blubber alloc] init];
aBlubber.aDate = [NSDate date];
[concurrentQueue addOperationWithBlock:^{
NSAutoreleasePool *blockPool = [[NSAutoreleasePool alloc] init];
NSDate *test = [aBlubber aDate];
NSLog(#"Block DONE");
[blockPool release];
}];
[aBlubber release];
[concurrentQueue release];
If I change the application to be a normal (i.e. non-backgound) application, I can observe the blocks being released whenever any input is made via the UI (even changing the focus to another window is sufficient).
Since my backgorund app receives input directly over the HID USB driver and it does not have a window or menu bar this does not happen.
Is there any way to manually force the runloop or whatever is responsible to telling the queues to release the finished blocks?
(All other objects that had been retained by the blocks are also not released, creating huge memory leaks. These leaks cannot be spottet by the Leaks or ObjectAllocations tools but the memory consumption can be observed skyrocketing using top.)
One common "gotcha" for autorelease pools is that if the app is building up memory without receiving events, the outermost pool (the one managed by the event loop) won't be draining.
I don't think that should apply here since you're managing your own pool... but just in case, you could try this:
...
//When no events are coming in (i.e. the user is away from their computer), the runloop doesn't iterate, and we accumulate autoreleased objects
[[NSTimer scheduledTimerWithTimeInterval:60.0f target:self selector:#selector(kickRunLoop:) userInfo:nil repeats:YES] retain];
...
- (void) kickRunLoop:(NSTimer *)dummy
{
// Send a fake event to wake the loop up.
[NSApp postEvent:[NSEvent otherEventWithType:NSApplicationDefined
location:NSMakePoint(0,0)
modifierFlags:0
timestamp:0
windowNumber:0
context:NULL
subtype:0
data1:0
data2:0]
atStart:NO];
}
It looks like you are using a stack based block that is used after the block has gone out of scope. The block needs to be copied. The code should work if it is changed to this:
[concurrentQueue addOperationWithBlock:[[^{
NSAutoreleasePool *blockPool = [[NSAutoreleasePool alloc] init];
NSDate *test = [aBlubber aDate];
NSLog(#"Block DONE");
[blockPool release];
}copy]autorelease]];
Take a look at this post for a full writeup on blocks: http://gkoreman.com/blog/2011/02/27/blocks-in-c-and-objective-c/