I'm displaying a modal view called "rule" from a round rect button. In that "rule" modal view i'm displaying another modal view called "newRule" when user clicks the Create Rule button.
When i'm quitting from the "newRule" modal view the app crashes. Here's the code i had written for quitting the "newRule" modal view.
[self dismissModalViewControllerAnimated:YES];
Nothing is displayed in the console. When i tried to debug the code, it displayed a EXC_BAD_ACCESS after the dealloc method. My dealloc method looks like this:
[label release];
label = nil;
[imageArray release];
imageArray = nil;
[languageElementsArray release];
languageElementsArray = nil;
[super dealloc];
Please help me.
Is the label a UILabel object? Also what are in the arrays? Views are automatically released once their superview is released, so releasing a subview after its superview has been released (or releasing the subview then the superview) will cause an crash similar to the one you describe
I'm experiencing something similar. When I comment out the last line ( [super dealloc] ), it then works. Does this make a difference for you?
If you happen to be using Automatic Reference Counting in Xcode 4.2, then you should not have a [super dealloc] at all—which would result in this error.
Of course, in that context you likely should not be releasing these other objects either.
Related
What am I doing is I am creating lots of UIView in the background and keep them in a NSMutableArray to use later. But when I dismiss the view controller I check the memory in Xcode and it seems some of memory not being released. I checked; view controller is being deallocated.
Check please:
This happend after several showing and dismissing the view controller. Some of them is being released but not all.
Thanks.
Uncheck Enable Zombie Objects option under Edit Scheme. And try again.
A zombie is an object that has been deallocated, but references to it still exist and messages are still being sent to it
I think this link has more info for you
What is NSZombie?
I suppose you use arc, so it might be useful to explicitly release this in dealloc.
-(void)dealloc {
for(UIView *vw in self.arrayOfViews) {
vw = nil;
}
self.arrayOfViews = nil;
}
Using dealloc is a bit like the old days (pre-arc), but it will help you manage memory better.
!important! --> NEVER call [super dealloc]; when using arc!
In dealloc method release all views that you have in the array.
called the below method in your controller dealloc method
- (void)releaseViewArray
{
// Releasing views in the array
for (UIView *view in _viewArray) {
[view release];
}
// Releasing the array that holding the views
[_viewArray release];
}
This is used to work fine for my pre-ARC code, but since refactoring all the project to be ARC compatible, I start getting this crash:
[CustomViewController respondsToSelector:]: message sent to deallocated instance
My project is an iPad app with a split view, but contrary to apple documentation, previous developer has put another view controller to be visible on app launch before split view. So I know this is not the right way to do, but as I said it used to work before ARC integration so I need to get a workaround with this.
The root view controller which contain a menu of items, each item display a detail form to be filled, then a click on next button move to the next detail screen, etc.
The issue starts when I click on home button put on root view to get back to the home view, here is the relevant code that move the user to the home screen:
//this method is in the appdelegate, and it gets called when clikc on home button located on the root view
- (void) showHome
{
homeController.delegate = self;
self.window.rootViewController = homeController;
[self.window makeKeyAndVisible];
}
Then when I click on a button to get back to the split view (where are the root/details view), the app crashes with the above description. I profiled the app with instruments and the line of code responsible of that is located in the RootViewController, in the didSelectRowAtIndexPath method, here is the relevant code:
if(indexPath.row == MenuCustomViewController){
self.customVC=[[CustomViewController alloc] initWithNibName:#"CustomVC"
bundle:nil];
[viewControllerArray addObject:self.customVC];
self.appDelegate.splitViewController.delegate = self.customVC;
}
customVC is a strong property, I tried to allocate directly and assign to the instance variable but that didn't help to fix the crash. Any thoughts ?
EDIT:
Here is the stack trace given by instruments:
[self.appDelegate.splitViewController setViewControllers:viewControllerArray];//this line caused the crash
[viewControllerArray addObject:self.appDescVC];//this statement is called before the above one
self.custinfoVC=[[CustInfoViewController alloc] initWithNibName:#"CustInfo" bundle:nil];//this statement is called before the above one
self.appDelegate.splitViewController.delegate = self.appDescVC;//this statement is called before the above one
custinfoVC and appDescVC are strong properties.
I solved this problem by setting my delegates and datasources to nil in the dealloc method. Not sure if it'll help you but its worth a try.
- (void)dealloc
{
homeController.delegate = nil;
//if you have any table views these would also need to be set to nil
self.tableView.delegate = nil;
self.tableView.dataSource = nil;
}
You may want to setup the CustomViewController during app launch, and display the other views modally on top if necessary. The error message you're getting is because something is getting released by ARC prematurely. It might have not manifested before because pre-arc stuff wasn't always deallocated immediately. ARC is pretty serious about releasing stuff when it leaves scope
Hard to tell without seeing a lot more of the code involved, and what line it breaks on, etc.
This:
- (void) showHome {
//THIS: where is homeController allocated?
homeController.delegate = self;
self.window.rootViewController = homeController;
[self.window makeKeyAndVisible];
}
EDIT:
Add this line right above the line that causes your crash
for (id object in viewControllerArray) {
NSLog(#"Object: %#",object);
}
I had the same Problem.If you are not using "dealloc" method then use "viewWillDisappear" to set nil.
It was difficult to find which delegate cause issue, because it does not indicate any line or code statement for my App So I have try some way to identify delegate, Maybe it becomes helpful to you.
1.Open xib file and from file's owner, Select "show the connections inspector" right hand side menu. Delegates are listed, set them to nil which are suspected.
(Same as my case)Property Object like Textfield can create issue, So set its delegate to nil.
-(void) viewWillDisappear:(BOOL) animated{
[super viewWillDisappear:animated];
if ([self isMovingFromParentViewController]){
self.countryTextField.delegate = nil;
self.stateTextField.delegate = nil;
}
}
Im setting an MaxIdleTime in my app once if no userInteraction happened within this specified time i'm just removing the existing view from my window and adding my login (Home) view as subview to my apps UIWindow through a method called logout.
In this logout i'm just removing all the references which are alive but if any of the UIPopOverController is visible on any view during this logout call i'm getting exception
-[UIPopoverController dealloc] reached while popover is still visible.
Im making popover instance to nil in viewDidUnload even though i'm getting this exception and app is crashing and my project is ARC enabled.
How to overcome this exception, any help is appreciated in advance.
To remove all the subviews in your main view when the timer fires, use the following code:
for (UIView *sub in [[_view subviews] copy]) {
[sub removeFromSuperView];
sub = nil;
}
As for the popovers, simply remove the one currently onscreen with:
[pop dismissPopoverAnimated:NO];
pop = nil;
I have a simple question regarding ARC. I show a UIView if a user taps a button using addSuperView within a UIViewController. The UIView contains a close button, if tapped I want to remove the view.
I used to call a method within the UIViewController after animating the view offscreen:
- (void)viewDidClose:(UIView *)view
{
[view removeFromSuperview];
[view release], view = nil;
}
Now using ARC I changed it to:
- (void)viewDidClose:(UIView *)view
{
[view removeFromSuperview];
view = nil;
}
The question now is: I want to remove the protocol and the delegation to the view controller and do this within the UIView itself.
Pre-ARC (within view):
- (void)didStop
{
[self removeFromSuperview];
[self autorelease];
}
I can't use 'autorelease' in ARC nor set 'self = nil', as far as I know ARC comes in place as soon as I set the view to nil or replace it, but what if I don't replace it? Is [view removeFromSuperview] enough to take care of everything or does this leak?
Thanks a lot! I appreciate any help!
(Note that in your non-ARC version, you'd want the autorelease before the removeFromSuperview).
I've wondered about similar things. The 'danger' is that when you do the removeFromSuperview without first doing an autorelease, the object is immediately deallocated, even before the end of the method. That's skeezy.
My idea was that you'd make the method return self. In the non-ARC case, you'd create this pointer with autorelease but ARC should do that for you. You may not need the pointer in the caller, but I believe this will force ARC to do what you want.
So I'm having problems releasing some view controllers.
In essence the dealloc for the PhotoPostViewController never seems to get called, so I can't clear down the images contained within that are munching all the memory.
This is my UIViewController subclass, I can have up to 100 of these at any one time added as subviews to the main scroll view, the iPad gets tight for memory after that.
#interface PhotoPostViewController : UIViewController {
IBOutlet UIImageView *backgroundImage;
IBOutlet UIImageView *serviceImage;
}
Then in my main view class I have a method to create these views and add them to a scrollView. This method is typically called from a loop to create all the subviews I need.
- (void) addPost {
PhotoPostViewController *postView = [[PhotoPostViewController alloc] initWithNibName:#"PhotoPostViewController" bundle:nil];
[scrollView addSubview:[postView view]];
[viewControllers addObject:postView];
}
viewControllers is an NSMutableArray created in the main class init.
scrollView is a UIScrollView on my main view.
This all works fine, I know the limit of the memory usage on the iPad and keep within that at any given time, opening Popovers to give preview images and videos etc...
Doesn't run out of memory until I try to refresh the screen.
The code to do this is:
- (IBAction)didPressRefresh:(id)sender {
for(UIView *subview in [scrollView subviews]) {
[subview removeFromSuperview];
}
for(UIViewController *c in viewControllers) {
[c release];
}
[viewControllers removeAllObjects];
}
For the sake of simplicity I clear off all the subviews and try to release them before recreating the next set of subviews using the function above.
It removes them from the view, but runs out of memory adding the new set of view controllers. In my test cases the sets of view controllers are identical in content, so if it loads from clean first time, then it should load the second time and every other time after that if I release everything properly.
What actually happens is it crashes due to low memory when creating the second set of view controllers.
While debugging I've put breakpoints on the 'viewDidUnload' and 'dealloc' methods, but they never get hit.
It looks like the UIViewController itself is getting released, yet the UIImageViews within are not, clearly they'd usually get released by my code in the dealloc (or viewDidUnload) method.
So I'm confused.
Counting things it looks to me like the reference counts are fine. so how come the dealloc is not getting hit ?
Andi
You need to send the postView object the -release message after adding it to the viewControllers collection:
- (void) addPost {
PhotoPostViewController *postView = [[PhotoPostViewController alloc] initWithNibName:#"PhotoPostViewController" bundle:nil];
[scrollView addSubview:[postView view]];
[viewControllers addObject:postView];
[postView release];
}
The reason why you need to do this is because the collection sends the -retain message to all objects that are added to it, hence the memory leak and -dealloc not being hit.
EDIT:
Your -didPressRefresh: method should look like this:
- (IBAction)didPressRefresh:(id)sender {
[[scrollView subviews] makeObjectsPerformSelector:#selector(removeFromSuperview)];
[viewControllers removeAllObjects];
}