Why objects are not dealloced in the dealloc method?

Question

I have a problem understanding the Objective-C and the ARC.

As I understood the strong pointers will be dealloced automatically for you, so you don't have to think about it (dealloced in dealloc method, or after the last time the object was used ?).

So I wrote a little app, with 2 viewControllers and a NavigationController, which enters one view and then goes back.

The dealloc method was called, but the property, which I set at viewDidLoad method, wasn't deallocated, it is still pointing to some object.

Code: The first viewController has a button, which by pressing it, performs a segue to another viewController. No code there.

SecondViewController.m

@interface SecondViewController () 
@property (nonatomic, strong) NSString *myString;
@end

@implementation SecondViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    NSLog(@"%@", _myString);
    _myString = @"it works";
}

- (void)dealloc {
    NSLog(@"%@", _myString);
    // and now it is deallocating the _myString property ???
}

@end

Then, I tried to do another thing.

The idea was to create a weak pointer, which points to the same memory address, as the strong pointer. I though, that the weak pointer should be nil in any case.

1. Since the dealloc method is called, all weak pointers should be niled

2. Since the strong pointer was used only in viewDidLoad, it should be deallocated way before the dealloc method.

The problem is, it is not deallocated. Why ?

Code for secondViewController:

@interface SecondViewController ()
@property (nonatomic, strong) NSString *myString;
@property (nonatomic, weak) NSString *test;
@end

@implementation SecondViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    NSLog(@"%@", _myString);
    _myString = @"it works";
    _test = _myString;
}

- (void)dealloc
{
    NSLog(@"%@", _test);
}

@end

Answer 1

Deallocation of the properties happens at the end of the dealloc method. If you overwrite the dealloc method, the properties won't yet be deallocated inside that method.

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You could test this by creating a weak property in your first view controller, assign the strong property of the second view controller, then log the value of it when the application returns to the first view controller.