On Nov 17, 2008, at 7:12 PM, Brian Stern wrote:
On Nov 17, 2008, at 9:11 PM, mmalcolm crawford wrote:
One other consideration, particularly in iPhone applications, is
where you might have outlets to subviews of a main view that might
be released in sime situations -- e.g. a UIViewController whose
view is released in didReceiveMemoryWarning. To ensure that you
don't prolong the lifetime of objects you got from the nib, you
should set (use your accessor methods to) set those variables to
nil in the relevant method, e.g.:
@interface MyController : UIViewController {
UILabel *label;
...
}
@property (nonatomic, retain) IBOutlet UILabel *label;
then
- (void)didReceiveMemoryWarning {
self.label = nil;
[super didReceiveMemoryWarning];
}
OK, this issue has come up for me very recently. It appears that on
iPhoneOS IBOutlets are retained, regardless of the presence of
properties.
No, on iPhone outlets are consistently *not* retained -- which is
precisely why you do need to retain top-level objects on iPhone. But
absent accessor methods, connections are made using KVC...
This is documented here:
<http://developer.apple.com/iphone/library/documentation/Cocoa/Conceptual/LoadingResources/CocoaNibs/chapter_3_section_4.html#//apple_ref/doc/uid/10000051i-CH4-SW6
>
Even worse, in the presence of an assign property the outlet is
still retained. Whatever code is retaining the outlets never
releases them. So it seems that client code must release all outlets.
As I stated originally, following the pattern I describe above makes
memory management consistent in all situations.
The documentation on this is vague, with a lot of 'should's and not
clear statements of what really happens.
The documentation at <http://developer.apple.com/iphone/library/documentation/Cocoa/Conceptual/LoadingResources/CocoaNibs/chapter_3_section_4.html#//apple_ref/doc/uid/10000051i-CH4-SW6
> is explicit, there are just many different situations to consider
if you don't follow the property pattern.
mmalc
Actually this isn't (only) related to didReceiveMemoryWarning (which
I hadn't considered related to this problem until you raised it).
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