i'm developing an iPhone project in which i enabled ARC, and when i run my project with instruments so many places it is showing 100% leak for ex:
-[self.navigationController pushViewController:secondPage animated:YES]; //100% leak
[self loadXML];//100% leak
even if i make secondPage object as nil after pushing and in viewDidUnload the leak docent get resolved. How can i solve these leaks?Any help is appreciated in advance.Thank You.
The Leaks instrument (in Instruments) will tell you exactly what was leaked, where it was created, record the stack, and (optionally) record every reference count operation. Learning to use it proficiently is highly recommended.
Related
I created a test project to confirm my memory leaks:
Project file: https://dl.dropbox.com/u/3703182/PickerView.zip
Basically a UIPickerView is connected to a datasource via IB. When it's connected to a datasource, it leaks. If not, no leak. I need to use a UIPickerView for an imminent app that needs to be released ASAP, unfortunately it guarantees a crash every 2 hours because of the leak. How can I use the UIPickerView despite the memory leaks without crashing?
EDIT:
It only leaks on device, not in simulator.
That is not a leak. It's an allocation.
If it was a leak it would show a red spike in the second row.
The real test for a leak is presenting and dismissing several times over. If you can do that and show that the allocations keep rising then there is a leak. Not otherwise.
Adding my comments as answer,
Your app will not crash due to this leak since it is a very small leak caused by framework which you dont have to worry about. The screenshot shows that it is in terms of a few bytes. If your app is crashing every 2 hours, that means there is something else which is using a lot of memory. Please check if you are using anything else in your code which could cause this and update the question with your finding.
In allocation tool, make sure you are checking the live bytes section and check how much it is going up. If it stays below 15-20 MB, you dont have to worry much anyways. Check this for more details about memory usage in app. Also check this XCode Instruments Allocations: Look at Live Bytes or Overall Bytes?.
This is the Apple library that is leaking. You cannot do anything about this. It is Apple's fault.
This isn't a leak you can control, it's internal... but this is a very small amount of memory and will not crash your application. I'd be interested in seeing what this looks like an hour in... Can you provide a backtrace of the crash? That would probably better help determine the real cause of the crash.
While developing apps in Xcode memory leaks are occurring. When I checked them in extended detail view they are showing different methods that are not related to implemented. How to exactly find out which object is leaking and where it is leaking memory.
When ARC is enabled we have to take care of memory leaks or not?
Even with ARC memory leaks can occur, it just inserts release and autorelease during compile time.
1. You must check for leaks using Build and analyze in XCode, shift+command+b you should be clearing those issues.
2. After that you can start using the instruments by using profile option command+i . This will point you to where the leak might be.
This link will help you too http://soulwithmobiletechnology.blogspot.in/2011/04/how-to-check-memory-leaks-in-xcode-4.html
Edit: Added some screenshots to hopefully make it clear.
During profiling after selecting leaks choose the call tree option and check the boxes hide system libraries , invert call tree and show obj-c only as shown in image below.
After double clicking the symbol name below you'll get the line where it is leaking.
You'll get something like this.
Yes, even with ARC there are memory leaks. ARC is not a garbage collector, it only inserts for you, at compile time, retains, releases and autoreleases in key positions. So although it does help the developer, you should be aware that memory leaks still exist (for instance circular referencing). You can start by using the Static Analyzer and correct any problem it shows you. You can then go to Instruments and choose Leaks.
I am using UIImage picker, Local notification, event calendar, Date Picker , Facebook Sharing, Sounds, Navigation controller , database . My application is crash after some time, the reason is not same, Some times memory is full and some times too manny other receive memory warning. Please guide me how can i generally remove the leaks?
Have a look at this Cocoa Tutorial: Fixing Memory Leaks With Instruments. Instruments is the way to go to find leaks.
More resources:
Finding iPhone Memory Leaks: A “Leaks” Tool Tutorial
Apple's official Memory Usage Performance Guidelines / Finding Memory Leaks
Use Intstruments with the Leaks profile... see this article Leaks!
1.first of all release the objects in the dealloc .
2.Go to the xcode there in mainmenu you find the build tab.In that pressed on the build and analyze .It gives the errors.Remove those warnings.
If you are using autorelease objects, make sure it gets released at the right time. If you can,try not to use Interface Builder, i feel something is fishy abt it when it comes to memory.
Check the NSString objects, they can have devastating effects if not released on time.
also remember [UIImage imageNamed#"abc.png"] caches the images which also causes running low memory warnings.
Try to create your view hierarchy programmatically.
i'm only create an project with a Utility Application template.
This template has a native memory leak when i push "info button" to
flip the view.
Anyone know how can i fix this leak ???
I just make an new project from this template,
i don't add new objects.
That might be a leak or it might not be a leak. If you were to add the backtrace of the allocation, that would be helpful.
More likely than not, it isn't a leak, but some bookkeeping information that is being stashed away by dyld that leaks/Instruments loses track of.
Given that it is 128 bytes and I'm guessing there is only one of them, I would encourage you to file a bug via http://bugreport.apple.com and then forget about it for now as, in the unlikely case that it really is a leak, you will be equally as unlikely to be able to fix it from within your application.
Hope this helps.
From: http://www.cocos2d-iphone.org/forum/topic/2460
"The simulator has bugs related to singletons and llvm stuff that are incorrectly reported by Instruments. Always check your leaks on the device itself."
Got the leak doing this:
XCode 3.2--
File, New Project, Navigation-based Application
Give it a name
Build It
Run With Performance Tools -> Leaks
When Instruments comes up, click on Leaks (you might have to click the little icon at the bottom that looks like four boxes within a box)
About 7 seconds after running you should see the leak:
-- Malloc 128 Bytes, some Address, 128 Bytes, CoreGraphics, open_handle_to_dylib_path
I traced it to this code in the AppDelegate:
//APPLE CODE
- (void)applicationDidFinishLaunching:(UIApplication *)application {
// Override point for customization after app launch
[window addSubview:[navigationController view]];
[window makeKeyAndVisible];
}
I broke out the navigationController (did a separate alloc and release) and COMMENTED OUT the addSubview: action - there was no leak - and, obviously, the screen was blank.
It wasn't until I attempted addSubview that the leak occurred. Since there are numerous ways to add a subview, I tried those. Each resulted in the leak or a blank screen.
I tried it on a real ipod touch. No leak was reported.
Probably just a simulator thing ...
Leaks has flagged open_handle_to_dylib_path in CoreGraphics for me as well; there is definitely something flagged here. Since it is merely 256 bytes at its heaviest, I fired off a bug report to Apple and called it done. You can then set a rule in Leaks' configuration to ignore the report.
As bbum pointed out, there might be serious voodoo at work. I seriously doubt Apple would let leaky frameworks go through QA -- especially since it's so easy to reproduce.
This must be a bug. It appears in Apple's own example, PageControl, found here:
http://developer.apple.com/iphone/library/samplecode/PageControl/index.html#//apple_ref/doc/uid/DTS40007795
In the current SDK utility template is no leak. How did you get the impression there's a leak in the template? It's just allocating memory which is needed for the views.
A leak is memory to which no pointers exist and which cannot be freed any more.
I had the same problem, but was able to understand why it happened. And I have given a brief info regarding this problem in this article
Might be useful for you.
I'm using the Leaks Instruments feature through Xcode to (try and) find memory leaks. I still haven't figured out how to use this program. I click Leaks in the program and see memory increasing as I do various things in the simulator. I have Extended Detail pane displayed. The only thing in Extended Detail pane that references my app is main. As in the main method produced by Xcode. Everything else is UIKit, Foundations, and other SDK classes I didn't write. What am I doing wrong that nothing is showing up from my app?
Before I hit 3 minutes, there are over 100 leaks totaling 2.5k. Is this common?
I've written up a Tutorial on using Instruments to track iPhone memory leaks. I'm not sure if it will help you with what you're dealing with or not...couldn't hurt, though. :-)
http://www.streamingcolour.com/blog/tutorials/tracking-iphone-memory-leaks/
Change the view to "Extended Detail" on the instruments panel. This will show you the stack trace of each leaked object after you stop recording and select the leaked object.
You do see calls into the API, but what you are interested in is finding the last method of your application before the API calls, that is where the leak is.
A tip: turn on "gather memory contents" in the leaks view. Seeing the object values should also help finding where the problem is.
You don't want any leaks. 100 leaks is not typical (at least in my apps ;) Typical should be 0.
I'm not familiar with how to use Leaks, but you can always try running the Clang analyzer on your code to see if that'll turn anything up: http://clang.llvm.org/StaticAnalysis.html. It can often find many bugs that might lead to memory leaks.
Xcode: run -> Start with Performance Tool -> Leaks
Keep in mind that the Simulator may leak when the device will not. Ran into that once already with UITableViewController class.
Use LLVM/Clang Static Analyzer.
Note also that the leak tool is not going to show you instances where objects are over-retained and still held on to. Leaks are cases where objects that should have been let go are just hanging around with no-one to clean them up. Over retained objects are validly held onto even though you'd think they should be gone - thus the leak tool cannot point them out, since they are still referred to and there's no way to tell them apart from objects that should still be retained.
To find those, use the memory reporting tool and make sure that memory use goes down fully after you free an object. If you notice something isn't freeing memory, you can start by putting breakpoints in dealloc to see if what you expect to see released is actually getting released.
You need to look for both cases to keep a clean memory footprint.
Run -> Start with Performance Tool -> Leaks
To detect memory leaks you can use the "build and analyze" function of Xcode.
Simply select Build -> Build and Analyze in the Xcode menu.
Made a sum up of the main memory leak tools: http://bcaccinolo.wordpress.com/2010/09/15/iphone-essential-performance-tools-list/
Leaks application that can be found in Xcode: run -> Start with Performance Tool -> Leaks.
Apple’s Instruments utility that can be found in /Developer/Applications/Performance Tools.
One of the best way to find the memory leaks is Select Product-> Analyze. In the left Xcode shows in which file you have memory leaks. What are the variable causing memory leaks. This is one of the best way to find memory leaks.
The memory debugger (button just over the console, next to the view debugger) is quite useful too.
It will show you leaks, and you can check /filter easily if objects are still in memory when they shouldn't.