i have a UIView [self] with 2 custome UIViews [articalBottomPanel] [movingSharePanel]
every custome view is declared in a single class
first view [articalBottomPanel] delegate's will be set to self
second view will take also [self.artical] , [self]
as here :
[self.articalBottomPanel setDelegate:self];
[self.articalBottomPanel.btnCommment addTarget:self action:#selector(commentBtnPressed:) forControlEvents:UIControlEventTouchUpInside];
[self.movingSharePanel setArtical:self.artical];
[self.movingSharePanel setParentView:self];
My dealloc is
- (void)dealloc
{
NSLog(#"ArticalViewController : dealloc");
[movingSharePanel_ release];
[articalBottomPanel_ release];
[super dealloc];
}
the problem is : when i pop the view [self] dealloc not called ?!
the question is : before pop this view [self] ,
is it want to do any releases more than the release at delloc ?!
Have you made delegate as #property(retain)? If yes then make it assign. If not then make sure your ViewController is released. Check if after pushing it, you release it or not.
retainCount is useless. Don't call it.
Specifically, the absolute retain count of an object is an irrelevant implementation detail that should generally be ignored (it is only useful if you also have an exact inventory of every retain/release, but if you have that, the retain count isn't useful, either).
See this answer for a brilliant explanation of how to track down exactly who/what is still retaining the object.
Related
I'm working on an app that has a Main view that wants to spawn a child view when a button is touched. So when I receive the button event, the MainViewController spawns the child view by calling initWithNibName and storing the ChildViewController in an ivar. I then show the ChildView by attaching an animation and setting childVC.view.hidden = NO.
This works, but I noticed that the ChildViewController was never getting released after closing the ChildView. I realized that the ChildVC's retain count went from 1 to 2 when I first access the child view. So something in the nib loading guts appears to be retaining my ChildVC again (in addition to the initial retain I expect during object initialization).
Can somebody help me figure out why the ChildVC is getting retained the extra time, and how can I make sure that it gets fully released when I want to close the child view?
Edit: here's some code, only slightly simplified. These are methods on the parent view controller.
-(IBAction)onLaunchChildButtonTouched:(id)sender
{
m_childViewController = [[ChildViewController alloc] initWithNibName:#"ChildViewController" bundle:nil];
[m_childViewController setParentDelegate:self]; // this is a weak reference
// m_childViewController retain count here is 1, as expected
m_childViewController.view.hidden = YES;
// m_childViewController retain count is now 2, not expected
[self.view addSubview:m_childViewController.view];
[self addTransitionEntrDir:YES]; // code omitted
m_childViewController.view.hidden = NO;
}
-(void)onChildWantsToClose:(id)child
{
NSAssert( child == m_childViewController, #"unexpected childVC" );
// if child view is now hidden, we should remove it.
if( m_childViewController != nil && m_childViewController.view.hidden )
{
[m_childViewController.view removeFromSuperview];
[m_childViewController release]; m_childViewController = nil;
// BUG: m_childViewController retain count is still 1 here, so it never gets released
}
}
Without code it is difficult to say exactly, but are you sure you are not assigning your ChildVC to a retain property of some other object? This would explain the unexpected retain you see.
Sorry for the previous answer, where I tried to convey this same message but I mixed everything up.
OLD ANSWER:
keep in mind that the view property of a UIViewController is retained:
view
The view that the controller manages.
#property(nonatomic, retain) UIView *view
so, if you assign to it like this:
childVC.view = [[xxxxx alloc] initWithNibName:...];
this explains what you are seeing.
Use instead:
childVC.view = [[[xxxxx alloc] initWithNibName:...] autorelease];
I found the problem, the leaky ChildViewController was instantiating an object that retained a ref back to it.
The interesting part is that I wasn't simply forgetting to release this reference. I did have a call to release it, but that code was never running because it assumed that viewDidUnload would run and give me a chance to release everything, but it didn't. I put me deinit code inside dealloc instead, and it works now.
I have a view controller named SettingsViewController, and a custom UIView subclass named ViewAccounts. In SettingsViewController, I am using the code below to add ViewAccounts view into SettingsViewController.
if(!self.viewAccounts)
{
ViewAccounts *objViewAccounts= [[ViewAccounts alloc] initWithFrame:CGRectMake(0, yViews, 320, 400) withViewController:self];
[self.view insertSubview:objViewAccounts atIndex:0];
self.viewAccounts = objViewAccounts;
[objViewAccounts release];
}
The Problem is that the dealloc method of ViewAccounts (subclass of UIView) is not getting called. If I comment these both lines of code, then dealloc method gets called.
[self.view insertSubview:objViewAccounts atIndex:0];
self.viewAccounts = objViewAccounts;
I guess the problem is with retain count, at it gets incremented by 1 when we use insertSubview or addSubiew, but how to get rid of it. Is this the right approach to use it?
Just as a note: making viewAccount to assign can cause a Zombie down the road (in the original code snippet) because you release it in the last line.
I would suggest the following approach:
Make viewAccounts retain again
Don't use autorelease because you are not returning it from that method
Pay attention to dealloc method of the method in the snippet
This is how I would write the snippet with viewAccounts retaining
if(!self.viewAccounts)
{
ViewAccounts *objViewAccounts= [[ViewAccounts alloc] initWithFrame:CGRectMake(0, yViews, 320, 400) withViewController:self];
[self.view addSubview:objViewAccounts];
self.viewAccounts = objViewAccounts;
[objViewAccounts release];
}
...
- (void) dealloc {
[super dealloc];
[viewAccounts release];
...
}
What happened in your original code was that the retaining variable viewAccounts was not released properly at the end of the this class life cycle and so dealloc was not called.
BTW when you only assign the variable then you have to manage the retain yourself if you re-assign that variable especially if you NIL it. Assume that you set the variable to NIL then the snippet could be executed again. But then you overwrite the variable and you are not able to release the first value. If you use retain the Object-C will do that for you. As a rule of thumb I would always use retain for properties until you have enough experience to handle the other cases.
You could set your objViewAccounts to autorelease, since it will be retained by self.view anyway.
ViewAccounts *objViewAccounts= [[[ViewAccounts alloc] initWithFrame:CGRectMake(0, yViews, 320, 400) withViewController:self] autorelease];
Also regarding the retain count, if the property self.viewAccounts is declared as retain, that would also increase the retain count by 1.
I am hoping to clarify the processes going on here.
I have created a subclass of UIButton whose init method looks like this:
- (id)initWithTitle:(NSString *)title frame:(CGRect)btnFrame {
self = [UIButton buttonWithType:UIButtonTypeCustom];
[self setTitle:title forState:UIControlStateNormal];
self.frame = btnFrame;
return self;
}
In my view controller I am creating one of these buttons and adding it as a subview:
myButton = [[CustomButton alloc] initWithTitle:#"Title" frame:someFrame];
[self.view addSubview:myButton];
In the view controller's dealloc method I log the retain count of my button:
- (void)dealloc {
NSLog(#"RC: %d", [myButton retainCount]); //RC = 2
[super dealloc];
NSLog(#"RC: %d", [myButton retainCount]); //RC = 1
}
The way I understand it, myButton is not actually retained, even though I invoked it using alloc, because in my subclass I created an autorelease button (using buttonWithType:).
In dealloc, does this mean that, when dealloc is called the superview releases the button and its retain count goes down to 1? The button has not yet been autoreleased?
Or do I need to get that retain count down to zero after calling [super dealloc]?
Cheers.
This deserves two answers.... one for the specific question and one for how memory is managed when the instance is replaced in -init (this one).
Initializers are an odd bird in the Objective-C memory management world. In effect, you are managing self. On entry, self is retained. On exit, you are expected to return either a retained object -- doesn't have to be the same object as self -- or nil.
So, breaking the standard idiom of [[[Foo alloc] init] autorelease] down:
id x = [Foo alloc]; // allocates instance with RC +1
x = [x init]; // RC is preserved, but x may differ
[x autorelease]; // RC -1 (sometime in future)
Note that all retain counts [RC] are expressed as deltas.
Thus, in the init method, you typically don't change the retain count of self at all!
However, if you want to return some other object, you need to release self and retain whatever you are going to return (whether allocated then or previously allocated somewhere else, say when an object is retrieved from a cache).
Specifically, with everything blown out into individual expressions because this answer is being overly pedantic:
- init {
[self release];
self = nil;
id newObject = [SomeClass alloc];
newObject = [newObject init];
if (newObject) {
self = newObject;
... initialize self here, if that is your fancy ...
}
return self;
}
This is more than a little bit tricky. I have summarized my answer in 5 parts:
Creating a custom init method that returns a different object
WARNING: beware of illegal memory access!
How to properly transfer ownership of the button to its parent view
Specific answers to specific questions
A suggestion for improvement
Part 1 : Creating a custom init method that returns a different object:
This is an example of a very special case, namely that the object returned from -initWithTitle:frame: is not the same "object" that was sent the message in the first place.
Normally speaking, the process goes like this:
instance = [Class alloc];
[instance init];
...
[instance release];
Of course, the alloc and init calls are usually grouped together into one line of code. The key thing to notice here is that the "object" (nothing more than an allocated block of memory at this point) which receives the call to init has already been allocated. If you return a different object (as in your example), you are responsible for releasing that original block of memory.
The next step would be to return a new object that has the proper retain count. Since you are using a factory method (+buttonWithType:), the resulting object has been autoreleased, and you must retain it to set the proper retain count.
Edit: A proper -init method should explicitly test to make sure that it is working with a properly initialized object before it does anything else with that object. This test was missing from my answer, but present in bbum's answer.
Here is how your init method should look:
- (id)initWithTitle:(NSString *)title frame:(CGRect)btnFrame {
[self release]; // discard the original "self"
self = [UIButton buttonWithType:UIButtonTypeCustom];
if (self == nil) { return nil; }
[self retain]; // set the proper retain count
[self setTitle:title forState:UIControlStateNormal];
self.frame = btnFrame;
return self;
}
Part 2: WARNING: beware of illegal memory access!
If you are allocating an instance of CustomButton, and then replacing it with an instance of UIButton, you could easily cause some very subtle memory errors. Let's say CustomButton has some ivars:
#class CustomButton : UIButton
{
int someVar;
int someOtherVar;
}
...
#end;
Now, when you replace the allocated CustomButton with an instance of UIButton in your custom init... method, you are returning a block of memory that is too small to hold a CustomButton, but your code will continue to treat this block of code as if it is a full-sized CustomButton. Uh oh.
For example, the following code is now very, very bad:
- (id)initWithTitle:(NSString *)title frame:(CGRect)btnFrame {
[self release]; // discard the original "self"
self = [UIButton buttonWithType:UIButtonTypeCustom];
[self retain]; // set the proper retain count
someOtherVar = 10; // danger, Will Robinson!
return self;
}
Part 3: How to properly transfer ownership of the button to its parent view:
As for your view controller's dealloc method, you will have to call [myButton release] if you have initialized the button as shown. This is to follow the rule that you must release anything that you alloc, retain or copy. A better way to deal with this issue is to let the controller's view take ownership of that button (which it does automatically when you add the button as a subview):
myButton = [[CustomButton alloc] initWithTitle:#"Title"
frame:someFrame]; // RC = 1
[self.view addSubview:myButton]; // RC = 2
[myButton release]; // RC = 1
Now, you never have to worry about releasing that button again. The view owns it, and will release it when the view itself is deallocated.
Part 4: Specific answers to specific questions:
Q: The way I understand it, myButton is not actually retained, even though I invoked it using alloc, because in my subclass I created an autorelease button (using buttonWithType:).
Correct.
Q: In dealloc, does this mean that, when dealloc is called the superview releases the button and its retain count goes down to 1? The button has not yet been autoreleased?
Also correct.
Q: Or do I need to get that retain count down to zero after calling [super dealloc]?
Sort of :) The retain count may or may not drop down to zero at the point when you log it. Autoreleased objects may still have a retain count of one, since they effectively belong to the autorelease pool for the current run loop. For that matter, the view itself may still belong to a window which has not yet been released. The only thing you really need to worry about is balancing out your own memory management. See Apple's memory management guide for details. From the point of view of your viewController, you have allocated the button once, so you must release it exactly once. When it comes to your custom init... method, things get a little bit trickier, but the principle is the same. A block of memory has been allocated, so it must be released (part 1), and, (part 2) init should return an object with a retain count of one (to be properly released later on).
Part 5: A suggestion for improvement:
You could avoid most of the custom initializer mess by simply creating your own factory method in the same spirit as the one provided by UIButton:
+ (id)buttonWithTitle:(NSString *)title frame:(CGRect)btnFrame {
UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
[button setTitle:title forState:UIControlStateNormal];
button.frame = btnFrame;
return button;
}
Note that this approach can still result in memory access errors as identified in part 2
First:
Do not call retainCount
The absolute retain count of an object is next to useless. There are always better ways to reason about memory management in your application.
Next:
Your initWithTitle:frame: method is allocating and returning an instance of UIButton, not an instance of the subclass. If that is what you want, there is no need for a subclass at all.
If you really want an instance of a subclass of UIButton, that is going to be more difficult. A quick google search and a read of the documentation indicates that UIButton really isn't intended to be subclassed.
I just tried:
#interface FooButton:UIButton
#end
#implementation FooButton
#end
FooButton *f = [FooButton buttonWithType: UIButtonTypeDetailDisclosure];
NSLog(#"%#", f);
And it printed:
<UIButton: 0x9d03fa0; frame = (0 0; 29 31); opaque = NO; layer = <CALayer: 0x9d040a0>>
I.e. the sole method to be used to create UIButton instances quite explicitly does not allocate via [self class]. You could go down the path of trying to initialize the instance by hand ala UIView or UIControl, but that is likely a lot of trouble.
What are you trying to do?
I'm running into a retain count issue that I do not understand. (I've added what I believe to be the retain count of vertex in [] at the end of each line of code).
CBVertex *vertex = nil;
for(int i=0; i<10; i++) {
vertex = [[CBVertex alloc] initWithFrame:CGRectMake(minX, y, 10.0, 10.0)]; // retain count [1]
[vertex setTag:i];
[vertex setAnimationDelegate:self];
[gameboard addSubview:vertex]; // retain count [2]
[tripGraph addVertex:vertex]; // retain count [3]
[vertex release]; vertex=nil; // retain count [2]
}
CBVertex is a subclass of UIView, gameboard is a UIView and tripGraph is a class that, among other things, has an NSMutableArray (privateVerticies) to which vertex is added to in its addVertex method.
After the above is executed, Instruments shows that there are 10 instances of CBVertex living.
Later in the code execution (I've confirmed that this code executes):
[[tripGraph verticies] makeObjectsPerformSelector:#selector(removeFromSuperview)];
// gameboard should have no references to any of the CBVertex's (correct??)
[tripGraph removeAllVerticies];
// tripGraph privateVerticies is empty and no references to any of
// the CBVertex's (correct?)
Relevant tripGraph methods:
-(NSArray *) verticies {
return [NSArray arrayWithArray:privateVerticies];
}
-(void) tripGraph removeAllVerticies {
[privateVerticies removeAllObjects];
}
- (void) addVertex:(CBVertex *)vertex {
[privateVerticies addObject:vertex];
}
The issue arises when the second set of CBVertex's are created. Instruments shows that the first set of CBVertex's is still live (i.e. the number of instances of CBVertexs is now 20).
I'm (obviously?) missing a release somewhere, but don't understand where . . .
Help/pointers are appreciated!!
thanks
tom
If gameboard and tripGraph are still retaining that CBVertex object, then even if you release it in your loop, it will continue to exist until you remove the CBVertex object from gameboard and tripGraph as well.
OK, I'm closing this out as the code above is correct. The problem lies in my overriden removeFromSuperview method in which there is an animation going on. I'm going to investigate further and if I don't have it figured out, I'll repost a new question. (and link to it from here).
Thanks for the comments, answer and several views.
For those interested, here's what was going on and how it was resolved.
In CBVertex, I've overridden removeFromSuperview. In that overridden method, I am animating the view's layer and setting the view as the CAAnimations delegate (which is retained by the CAAnimation) and calling super removeFromSuperview. The animation is not removed on completion.
As the animation retains the delegate and the animation is not removed, the view's retain count remains at +1.
My resolution was to create an intermediate method to perform the animation. When the animation is complete it calls the overriden removeFromSuperview, which now only removes all animations and calls super. Removing the animation releases it, which in turn releases it's reference to it's delegate (the CBVertex) and the CBVertex's retain count goes to +0.
One final thought for anyone chasing retain counts: don't think of them as absolute values. The inner workings of the objects you may be using might be retaining your instances more than you'd expect -- think of retain counts as a delta.
SomeClass *myObject = [[SomeClass alloc] init]; // retain count +1
[someMutableSet addObject:myObject]; // retain count +2
I want to change an image on a view, from a popup dialog of 4-6 icons (imagine like changing your image on a messenger application).
The way I implement this modal popup is by creating a new view at IB, with opacity on the background, and then I load this as a subview:
IconsViewController *iconsViewController = [[IconsViewController alloc] initWithNibName:#"IconsView" bundle:nil];
[self.view addSubview:iconsViewController.view];
So, when the user touches an icon, I have
- (IBAction)iconIsSelected:(id)sender {
switch ([sender tag]) {
case 1:
[(ParentViewController*)[self superview] changeIcon];
break;
case 2:
// same here..
break;
default:
break;
}
[self.view removeFromSuperview];
[self release];
}
The changeIcon just sets the image to a corresponding icon.
As you can guess, this is not working - the changeIcon message never works.
I can't understand what am I doing wrong, any help much appreciated!
You have a few choices here...
First one is create a property on your IconsViewController of type ParentViewController*, for example:
#property (readwrite,nonatomic,assign) ParentViewController* parentController; // weak reference
To break this down further:
readwrite because we want to be able to access the value via [self parentController] but also change it via [iconsViewController setParentController:self]
nonatomic because I'm not too worried about threading
assign to make it a "weak reference" where the parent will not be retained by the child. If they each retain the other, it could lead to memory leaks later because unless explicitly released you'd end up with a retain circle causing neither object to hit a zero retain count.
When you load from nib, set the property:
IconsViewController *iconsViewController = [[IconsViewController alloc] initWithNibName:#"IconsView" bundle:nil];
iconsViewController.parentController = self;
Then, call to it from inside of iconIsSelected like this:
[[self parentController] changeIcon];
Alternatively, you can create a delegate protocol:
#protocol IconViewSelectedDelegate (NSObject)
- (void) changeIcon;
#end
And use that protocol as a property, instead of the parent view controller type. This is more abstract, but it keeps the design cleaner. The parent view controller would then implement that delegate protocol, as one of many others.
Another option is to use NSNotificationCenter and publish/subscribe to events from your dynamic view. This is the "loosest" coupling between the two objects, but it might be overkill for this scenario.
The superview of a view is a view, not a view controller, yet you cast the superview to be of class ParentViewController. If the view has no superview, it returns nil, and message to nil are no-ops (which explains why you don't crash there).
BTW, that [self release] at the end is highly suspicious.