Question

I have a custom view class which is a subclass of UITableViewCell.

I have two other custom view classes which inherit from this subclass (they share a lot of the same properties but were different enough to warrant separate classes).

I’ve declared the shared properties in MyParentCell and also declared their unique properties in the respective classes.

UITableViewCell
      |
      |
 MyParentCell // defines propertyA and propertyB, both IBOutlet subviews
     / \
    /   \
   /     \
  |       |
  |     ChildClass1 // defines propertyC, an IBOutlet subview
  |
ChildClass2 // defines property D, an IBOutlet subview

My question is: Since I’m using ARC and cannot explicitly call [super delloc]; when I’m defining dealloc: in ChildClass1 and ChildClass2 do, I have to release all of the subviews they own in each class, or will MyParentCell#dealloc still be called too?

i.e.,

Do I have to write this:

// ChildClass1.m
@implementation ChildClass1

-(void)dealloc
{
    self.propertyA = nil;
    self.propertyB = nil;
    self.propertyC = nil;
}
@end

// ChildClass2.m
@implementation ChildClass2

-(void)dealloc
{
    self.propertyA = nil;
    self.propertyB = nil;
    self.propertyD = nil;
}
@end

Or is it enough to write:

// MyParentCell
@implementation MyParentCell

-(void)dealloc
{
    self.propertyA = nil;
    self.propertyB = nil;
}
@end

// ChildCell1.m
@implementation ChildCell1

-(void)dealloc
{
    self.propertyC = nil;
}
@end    

// ChildCell2.m
@implementation ChildCell2

-(void)dealloc
{
    self.propertyD = nil;
}
@end

If the second approach is fine, can someone explain when and how MyParentCell#dealloc is called?

If the first approach is necessary, that sucks :/

Answer 1

Of course, also with ARC every class is responsible to clean up only its own resources. If you define a dealloc in a subclass, it’s calling the parent’s dealloc implicitly at the end of your method. You just don’t have to type it.

If you just release instance variables or properties, you can rely on ARC to do this for you after the whole dealloc chain is done. ARC silently implements .cxx_destruct which gets called from NSObject’s dealloc and takes care of releasing anything strong in your class.