I'm trying to remove a UITabBarController from a window in my app by calling removeFromSuperview on the controller's view after adding it to the window previously. However when i do so and after it deallocates all the view controllers that are on the bar successfully, i get an EXC_BAD_ACCESS signal after an autorelease pool is drained. by method swizzling i've found out that it happens after something called UITableViewRowData has its dealloc method called. I'm wondering if there's a bug when the more view controller is attempting to be deallocated. Has anyone else ever run into this problem?
You are most likely releasing something you shouldn't be, can't really say what without some sample code
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I'm working on an app where different view controllers get pushed and dismissed via dismissModalViewControllerAnimated.
I'm having some memory issues with the app just crashing after a while. Looking at the Leaks instrument, I see that my overall allocations keeps going up and up. Even after the viewcontroller is dismissed, memory does not go down.
Are there any obvious reasons for this? What is the simplest and easiest way to find out why my app is crashing? Thanks
POSSIBLE SOLUTIONS
I went through some trial and error as well as googling and made a few changes:
1) A delegate relationship may have been retaining the viewController, so I changed the object's delegate property to weak.
2) NSTimer's should be invalidated before dismissing viewController.
3) UIView animations may interfere with dealloc being called? You can use [view.layer removeAllAnimations] to end them before popping your viewController.
If your memory is not go down after the dismissModalViewControllerAnimated .. it means you are creating the Global Object of the ViewController And after dismissing you are not setting the Object = nil;
If you set nil then your memory goes down automatically.
I've been facing a weird issue with dismissing a modal view.
I present a modal view like this:
ResepiDetail *detail =(ResepiDetail*)[[ResepiDetail alloc]init];
[self presentModalViewController:detail animated:YES];
and dismiss it like this with a back button:
[self dismissModalViewControllerAnimated:YES];
after this the view dismisses itself and goes back to the previous view, but it doesn't release itself from memory. I found it out by sending a notification message and that view received it. Additionally I tried to track the VM memory Allocation, and it seems the view is still in memory.
I'm using ARC and have the same method used for another view which works perfectly.
The code is fine, as posted, so here's some hints on how to proceed:
A sure fire way to be certain your view controller hasn't been deallocated is to override dealloc and log something identifiable. You can still do that in ARC, just don't explicitly call super. If you don't see the log when you expect to, then you have a problem.
Assuming that you have determined that you absolutely do have a problem, then the issue becomes finding the retain cycle. If the issue is that an instance of ResepiController isn't being dealloc'd, then you need to look for...
Any code outside the ResepiController class that has a strong reference to it. For example, if your class signs up as the delegate of some other class, make sure the delegate isn't using a strong reference.
Any internal blocks that may have implicitly retained self. Are there any blocks anywhere in your program that may have a reference to your controller at the time that you think it should be released?
I have what seems like a weird (non?) issue with UIViewController. It appears that the controller is not releasing its subviews when it is dealloc'd. I placed NSLog messages in all of the subview's dealloc method as well as the view controller. The view controller dealloc gets called but the subview's do not. However, if I then push another instance of that view controller on to the navigation stack, it appears that all of the subviews of the previous instance are then released (I get a bunch of NSLog messages in the console letting me know). I've check and I have no separate reference to the custom view controller in the presenting view controller (the one that's doing the pushing).
One small (maybe) detail: The custom view controller does receive a block it stores and then executes before popping. However, I did send nil to it and I get the same behavior. Plus, the presenting view controller does dealloc when popped of the stack, so no retain cycle.
Also, I did try explicitly releasing each view in the dealloc method of the custom view controller. Same behavior.
Is it possible the navigation controller would be holding on to it? It doesn't seem to do this to any of my other view controllers.
My problem is that this does represent a memory leak (of all those subviews); though the leak doesn't stack, it's still a leak.
Ok, this is embarrassing. I did find the problem in another class (called ViewDef) I was inadvertently using as a collection class. It was a quick and dirty way of keeping track of my subviews when I was first figuring out some animations (months ago). ViewDef stored frame/font/color/etc info retrieved from a database, so it was convenient to also store the views when figuring out animations (between orientations). These ViewDefs were being store by my model and passed around, so of course the views were also being retained (and replaced later by another view controller). Anyway, I forgot to insert a warning in my code to fix this later.
Moral of the story: If you plan on doing something stupid, at least document your stupidity so you don't have to broadcast it over the internet later.
you could try setting the subviews to nil in the viewDidUnload method maybe that will help
One thing to try is to make sure all your subviews delegates are set to nil.
I have a MainViewController, from which a new VideoPageViewController is presented modally.
In the ViewPageViewController, it will load a web page and launch the video, which is a heavy operation and sometimes causes memory warning. When it is ready to return to the MainViewController by dismissModalViewController, it says the MainViewController is already deallocated! The app thus crashes.
This happens sometimes, but not always.
Is there any exception handling I can take on it? Can I recreate the parent view controller? HELP!
Thanks
Just retain the MainViewController so it's not released when that happens.
You can probably do that in your application delegate, or in the class that owns it.
Remember to release it when/if you are done using it, so it's properly disposed of.
I've got next question - why my app dont waiting when i call
[navController popToRootViewControllerAnimated:NO];
... set new viewcontrollers here
I want:
1/ Kill all viewcontrollers by call popToRootViewControllerAnimated - with NO parameter - then i think i can immediately set new view controllers
2/ set new view controllers
But in my logs i see next:
call poptorootview controller
code after poptorootview
dealloc of views and controller (because i call poptorootview)
Why ? How can I detect that all views is killed and navigation controller is poping to root ?
Thanks,
A popped view controller will eventually be released (unless another object retains it), but the reference does not specify exactly when and how it is released. I wouldn't be surprised if it is not immediately released; the UIKit objects may use the view controller for the transition animation. It may be autoreleased not released, which may explain your logs. Also, I wouldn't be surprised inside UINavigationController multiple objects are retaining view controllers in the stack at the same time. Concisely speaking, there is no documented behavior about releasing popped view controllers. All we can be sure of is that it will be released at some point, as otherwise it will lead a memory leak.
Therefore you don't know when the view controllers are actually deallocated. Even if you find out it is subject to change without a notice. However, you can be sure when the view disappeared, using UINavigationController's delegate methods.