I have several memory leaks when testing my IOS application in xcode instruments. Can anyone see why the lines marked with "-->" are leaking?
--> CLLocationCoordinate2D newCoord = CLLocationCoordinate2DMake(latitude, longitude);
--> MapAnnotation* annotation = [[MapAnnotation alloc] initWithCoordinate:newCoord];
[mapView addAnnotation:annotation];
[annotation release];
also, I seem to have some structs which are leaking too;
--> double placeLat = [place.latitude doubleValue];
there is no pointer to the "placeLat" variable, so I can't release it? : /
thanks
Christy
Your code is correct, as much as you show of it.
One thing you have to keep in mind is that Leaks will show you the place where the leaked object is created, not the place where you do something wrong that will produce the leak.
This is an important difference. Indeed, it could well be, in the first case, that is the very annotation object which is leaked somewhere else in your code. You should check all the flow of execution that Instruments is showing you as stack trace.
Related
I am developing an application on iOS8 based on reactive cocoa. The application mainly does network operations.
I noticed that when all my signals complete and all signal references are nulled, i see a few RAC* objects still alive in the memory when i checked through instruments. Is this intended or is my code leaking memory? When i run the signal, there is an activity surge where i see a lot of RAC objects getting allocated and then it falls back to this state as shown the the below screen capture.
Every subsequent invocation ends in this same state. So i am not very worried about it btw.
http://imgur.com/sCL8Y3p
Thanks,
Those are all shared global instances that RAC uses so it doesn't need to allocate memory for every use of them. I'm sure there's a fancier word for that optimization, but I can't think what it is. For example, check out RACUnit:
+ (RACUnit *)defaultUnit {
static dispatch_once_t onceToken;
static RACUnit *defaultUnit = nil;
dispatch_once(&onceToken, ^{
defaultUnit = [[self alloc] init];
});
return defaultUnit;
}
Since all RACUnits are the same, RAC never bothers to make more than one instance of it. That's all you're seeing.
I am creating an application with ARC enabled and iOS 7 only. My all properties are properly marked as weak and all strong variables are marked as nil where I need it.
When I run my application with Instruments I found that memory allocation is continous increasing. When I go to any screen the memory increases (approximate 2 MB). When I pop that view the memory gets down to only few KBs. I don't know what happening.
while poping a view I am using following:
UPDATE:
[UIView animateWithDuration:0.5 animations:^{
CGRect newFrame = aSideMenu.view.frame;
newFrame.origin = SIDE_MENU_VIEW_ORIGIN_FINAL;
[aSideMenu.view setFrame:newFrame];
} completion:^(BOOL finished) {
[sender setUserInteractionEnabled:YES];
}];
Here I am using aSideMenu in block. aSideMenu is strong variable. Do you think I need to create it's weak reference and use?
__weak id aWeak = aSideMenu;
and use this aWeak instead of aSideMenu?
Also In few block I am using:
NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:....nil];
Should I pass weak reference of `dict' too?
I am not sure if this is the reason. Please help me to track the issue. Also let me know if anything else needs to add in this question for better solution.
Thanks
It would be great if you paste your code also. Without code I can just give you some tips.
Like never try to access strong pointer of self in block. Before entering in a block create weak pointer of self.
__weak id weakSelf = self;
and then use weakSelf inside the block.
Better also test your app for unbounded memory growth, where allocated memory never get chance to dealloct, you can take footprints by using Allocation instrument.
Update:
YES because you are calling setter method on strong pointer, it will retain it. You have to make them __weak or __block if they are shared.
https://developer.apple.com/library/ios/documentation/cocoa/conceptual/Blocks/Articles/bxVariables.html#//apple_ref/doc/uid/TP40007502-CH6-SW1
After having some more code, I want to make some thing more clear about the referenceing in block.
Memory issue may arrise when you reference some strong pointer inside block, as block will not let them deallocat, as they have valid reference, this is the major reason of memory issues. For that we have we create a weak pointer by using __weak id so I will not create a retian cycle.
But there is another issue if object have no other vaild reference, It will be deallocated and weak reference will be nil and it can cause a crash.
So good practice is to create a strong reference to weak in side the block and check for the nil.
I cannot find any detailed apple documentation on how the NSZombie really functions. I understand that its designed to not actually release objects and just maintain a count of references to catch any extra releases, but how would something like this work:
for(int i = 1; i < 10; i++)
{
NSMutableArray *array = [[NSMutableArray alloc] initWithCapacity: i];
[array release];
}
Since the same variable/object is being allocated/initialized and released in the same application, how would NSZombie's technically handle this? I know that this shouldn't flag any zombies because every alloc has a release, but how would Xcode technically handle re-allocating the same memory with different capacities?
With Zombies, objects don't actually need to be freed[1] -- the object is simply turned into a "Zombie" at some point after the object's retain count reaches 0. When you message a "Zombified" instance, a special error handler is performed.
1) Freeing Zombies is optional. Unless you really need the memory for a long running or memory intensive task, it is a more effective test to not to free the zombies (NSDeallocateZombies = NO)
This question was answered in the comments by Brad Larson.
Quote:
That isn't the same object, or the same memory. You're creating a distinct, new NSMutableArray instance on every pass through that loop. Just because a pointer to each is assigned to array does not make them the same object.
A pointer merely points to a particular location in memory where the object exists. A given object in memory can have multiple pointers to it, or even none (when it is being leaked). NSZombie acts on the object itself, not pointers to it.
I am stuck with the Cocoa Memory Managagment.
- (IBAction) createPush:(UIButton *)sender {
[create setEnabled:NO];
[release setEnabled:YES];
aLocation = [[Location alloc] init];
// Put some Example Stuff in the Class
aLocation.title = #"Apartment";
aLocation.street = #"Examplestreet 23";
aLocation.zip = #"12345";
aLocation.city = #"Exampletown";
aLocation.http = #"http://google.com";
aLocation.info = #"First Info Text";
aLocation.info2 = #"Second Info Text, not short as the first one";
aLocation.logoPath = #"http://google.de/nopic.jpg";
[aLocation.pictures addObject:#"http://google.de/nopic.jpg"];
[aLocation.pictures addObject:#"http://google.de/nopic.jpg"];
}
- (IBAction) releasePush:(UIButton *)sender {
[release setEnabled:NO];
[create setEnabled:YES];
[aLocation release];
aLocation = nil;
}
This Code works fine if I set or get Variables, but when I call the 'last' release (so the retain count is 0) it dealloc Method of aLocation gets called, but in Instruments Allocations you see that no memory is given back.
Here the Sources of Location:
http://homes.dnsalias.com/sof/Location.m
same Link with a '.h' instead of '.m' for the Header file (sorry its because of the Spaming Rule).
And the whole Project: http://homes.dnsalias.com/sof/Location.zip
Thanks for any help, where is my failure? Dennis
This Code works fine if I set or get
Variables, but when I call the 'last'
release (so the retain count is 0) it
dealloc Method of aLocation gets
called, but in Instruments Allocations
you see that no memory is given back.
What do you mean by "no memory is given back"?
Though oddly named, the memory management of aLocation is correct is the above code (assuming you have released it in dealloc as well).
Why doesn't memory use decrease when a single object is released?
(Paraphrased)
It is likely that your object is relatively tiny and, thus, that single deallocation falls below the ~20K or so needed to show up in Instruments.
If your app is crashing due to memory use issues, looking to a single deallocation is the wrong place to start. The first thing to do is to answer why your app is accreting memory and what is responsible for that growth.
Configure the Allocations instrument to only track live allocations. Then sort by total memory use. That'll show you what type of allocation is consuming the most memory. Start by reducing that.
Heapshot analysis can be very effective in these situations.
Additional Infos here because of maximum number of links and I have'nt the opportunity to post images...
What do you mean by "no memory is given back"?
I will show you the Instruments run, then it should be clear.
Screenshots from Instruments run
If want more Detail klick here for Instruments Run.
Your code is just fine. You are mistaken the output from Instruments. There is no Location object leaking.
For leaks, use the "Leaks" instrument. It won't fire. :-)
I've written a simple program in C and objC with a leak, and I cannot understand Leaks.
here it is:
int main(void)
{
int t = 78;
t = malloc(50);
t = 4;
return 0;
}
Can it show me which variable is the leak, or where it leaks?
Every Leaks tutorial on the internet (all two of them) are bad.
please help?
If you are testing the Leaks instrument with the code you provided, it is no wonder that it can't uncover any problems.
Leaks has a default snapshot interval of 10 seconds. But your program won't even run for 10s.
You are allocating in the scope of the application's entry point. "t" is valid (when not freed) until main exits. So the OS would reclaim the memory anyway.
And foremost: Your code does not contain a leak. It would be a leak if you "loose reference" to t. (e.g. by doing another t = malloc() or assigning t some other variable)
If you want to see Leaks in action, create a default Cocoa Application, add an instance variable "test" to your AppDelegate and put the following code into the implementation.
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
test = malloc(50);
test = malloc(20);
}
I've not used Leaks, but there are plenty of tutorials on the net, starting with Apple's - Apple's developer documentation on the subject, Mobile Orchard and Cocoa is my Girlfriend, which seems to be the best.