An application that I am working on, that uses ARC and needs to support iOS 4.3 and iOS 5, declares every outlet as @property (strong, nonatomic) IBOutlet in the .h file.
e.g.
// myClass.h
@property (strong, nonatomic) IBOutlet UITextView *myTextview;
I know that with ARC only properties which do not hold a strong reference to an object are released.
As a result, the App relies on - (void)viewDidUnload to set the property myTextview to nil.
i.e.
// myClass.m
- (void)viewDidUnload
{
[super viewDidUnload];
self.myTextview = nil;
}
I know, from Apple's Documentation, that Outlets should generally be weak except those from File's Owner ( i.e. A Runtime Object that owns the contents of the iOS Storyboard scene) to Top-Level Objects (my rule of thumb is to use anything that appears in the window with File's Owner, First Responder and View).
Anything I add to the view will be a subview and thus is retained by it's direct superview, meaning a weak reference should be used.
I am also aware that - (void)viewDidUnload is deprecated in iOS 6 and is not called.
1st Question : What are the issues with taking the approach of declaring every outlet as a strong property and setting it to nil in viewDidUnload, apart from the fact that viewDidUnload is deprecated in iOS 6?
My intuition tells me that it is because situations arise where you can set a pointer to nil, before viewDidUnload is called. So you should, to free up memory on the heap. Is there a noticable performance change if this is the case?
2nd Question : Should I go back throughout the project and change strong to weak? Why? Is it worth the time?
3rd Question : If I was to declare the property in a class extension, to 'hide' it, how does this affect my rule of thumb for deciding on when to use strong or weak.
I know there are many threads here that discuss this issue. But many I've found are out of date, and do not address this issue directly. Thanks.