I am creating a subclass of a custom UITableViewCell. The superclass has some properties that it is releasing in the dealloc method. I have added one additional property in my subclass, so I made sure to override the dealloc method and release my new property.
My question is, since I overrode the dealloc method, will the properties that were released in super class dealloc method not get released (I AM calling [super dealloc])? Do I need to specifically release those in MY dealloc method?
If you are calling [super dealloc], then the superclass implementation of -dealloc will still be run. The superclass should be responsible for releasing its own properties. So no, you don't need to release the superclass properties. In fact, doing so will likely cause your application to crash.
If you are calling [super dealloc], you are fine. That method won't know if it was called by a subclass or directly by the runtime, and it will do its usual work and take care of its own properties as always.
Important: Call [super dealloc] last in your -dealloc method, after you've your own ivars and done anything else you need to do in -dealloc. There won't be anything left of your object when that method returns.
Related
So, I have class:
#interface Controller : NSObject
{
UILabel* fileDescription;
}
#property(strong, nonatomic) UILabel* fileDescription;
Do I need use method dealloc where property fileDescription will equal nil?
For example:
-(void)dealloc
{
fileDescription = nil;
}
If not, who will dismiss memory used by fileDescription?
Generally you don't need to provide a subclassed dealloc method as ARC manages the lifetime of the instance variables.
However it can be useful to perform clean-up other than releasing objects, for example to remove an observer or close a network connection down cleanly. You are therefore allowed to subclass dealloc under ARC, but you are not allowed to call [super dealloc] from within the subclassed method.
In your particular case it's not required, however.
No.
You don't need dealloc method in ARC.
But if you want to do some cleanup tasks when your view is dismissing or released. It's the best place, In such case you can implement it.
For example:
You are running a timer in your view and it's updating your view. When you are dismissed the view you need to stop that timer. In that condition you can use dealloc method and stop timer there.
Similar for NSNotification observer.
If you are using ARC.
No need to use dealloc and release, compiler knows that your property and objects are strong / weak so it will manage it.
EDIT:
dealloc method is required if you use coreframework objects like CG... & CF.... Even you create observers for notifications you need to remove it and dealloc is the best place to removeObserver.
Ans is NO Because with ARC no need to dealloc.
As you are using ARC you don't have to use dealloc
Complier will set the autoreleasePool depending upon the scope of the property,variable or control. And it'll will release the memory. There are different types of autoreleasepool generally we can define them as function level,class level etc etc. Hope this helps.
I am new to iphone and I want to know when does -(void) dealloc method call. I know it is used to release objects but can we release any kind of object using dealloc method? And is it necessry to add this method and why we write [suped dealloc] in dealooc method?
share your views.
Here is the explanation straight from APPLE's Docs
The NSObject class defines a method, dealloc, that is invoked
automatically when an object has no owners and its memory is
reclaimed—in Cocoa terminology it is “freed” or “deallocated.”.
Important
Never invoke another object’s dealloc method directly.
Here is the answer why we call [super dealloc]?
You must invoke the superclass’s implementation at the end of your
implementation. You should not tie management of system resources to
object lifetimes
When an application terminates, objects may not be sent a dealloc
message. Because the process’s memory is automatically cleared on
exit, it is more efficient simply to allow the operating system to
clean up resources than to invoke all the memory management methods.
You Can release object those which is allocted, copy, or retain by you this is simple to understand. You can not release object those are not allocating by you means autorelease object, which ios detect for no more use in memory ,that time autorelease pool drain that time those object released from memory automatically.
And object dealloc method called when object retain count becomes zero.
You never send a dealloc message directly. Instead, an object’s dealloc method is invoked indirectly through the release NSObject protocol method (if the release message results in the receiver's retain count becoming 0). See Memory Management Programming Guide for more details on the use of these methods.
Subclasses must implement their own versions of dealloc to allow the release of any additional memory consumed by the object—such as dynamically allocated storage for data or object instance variables owned by the deallocated object. After performing the class-specific deallocation, the subclass method should incorporate superclass versions of dealloc through a message to super:
Refer this Link
Is it safe to do something like:
- (void) viewDidUnload {
[self cleanup] ;
[super viewDidUnload];
}
Because I hear things such as "self" may not even exist in a non-corrupt form when the view is unloading, hence it may be unsafe. Is it safe?
It's totally safe. viewDidUnload gets called in low memory situations when the view controller has temporarily deallocated the view to conserve memory. You just don't want to do anything in there that would access your controller's view property, as that would cause the controller to lazy-load the view again. Other than that, calling methods on self in viewDidLoad is totally safe.
You may be thinking of the dealloc method. I've seen people assert that you shouldn't call methods on self in your init or dealloc methods because your object may be in a partially initialized/released state. I guess the fear is that someone will try to modify or override the method you're calling without realizing that it's being called on a partially-formed object. This risk is increased if you don't set your released properties to nil in dealloc.
I made a static mainmenu with a TableView. Sometimes it crashes because my Subview has allready deallocated a subview.
Is also ok to release a View in the dealloc method of the local object instead of that:
[NavController pushViewController:self.AnotherView animated:YES];
[self.AnotherView release]; //This line into (void)viewDidLoad
AnotherView is defined in the headerfile as property and also synchronozed in the .m-File
When i use the dealloc way it works great on the device, but I need to know if this is correct.
You only call release for objects you init or alloc yourself. If it is a property of your class then release in the dealloc of your class.
So in your case, unless you init anotherView a few lines above your sample code (same method), calling release on it where you are is going to cause a leak/SIG_ABORT because you have done so prematurely.
Feel free to post more code, particularly how anotherView is assigned and you may get a more specific answer.
I have a very basic data class that is subclassed from NSObject. I declare a few strings, make sure they have properties (nonatomic, copy), and synthesize them. The only method I implemented was dealloc() which releases my strings. Can any memory problems arise from just this? Are there any other methods I need to implement?
Subclassing NSObject is something that we do all the time. Just follow the memory management rules, and you're good to go.
You could implement a custom init if you want to set anything up.
-(id)init {
if (!(self = [super init]))
return nil;
// Set things up you might need setting up.
return self;
}
But that's only if there's something you want to have ready before you call anything else on the class.
Just having a dealloc method should be fine, otherwise.
There won't be any problems. Subclassing NSObject is perfectly accepted, and in 99% of cases required.
By subclassing NSObject, your subclass receives all the required behaviour that is expected of any object in Cocoa/Cocoa Touch. This includes things like the reference counting memory management system using retain and release etc.
What you're doing is fine. Be sure to call [super dealloc] at the end of your subclass' -dealloc method.