在调用popToRootViewControllerAnimated：YES后在self.navigationController中取消分配或删除ViewControllers

Question

I am using a logout button that calls the

[self.navigationController popToRootViewControllerAnimated:YES];

method. After this is called I want to dealloc or remove the previous ViewControllers stored in the 'stack' of self.navigationController.viewControllers

I have tried a couple of ways to delete the 'stack', one by:

NSMutableArray *stack = [[NSMutableArray alloc] initWithArray:self.navigationController.viewControllers];
[stack removeAllObjects];
self.navigationController.viewControllers = stack;

so far nothing I've done deletes the stack. And I know they are not being deleted because I test it by

NSLog(@"%d", (int)self.navigationController.viewControllers.count);
[self.navigationController popToViewController:self.navigationController.viewControllers[2];

and it still pops to the ViewController.

any ideas?

---

Update: Logic in the calls

ViewController that calls the Pop method

[self.navigationController popToRootViewControllerAnimated:YES];

RootViewController

NSLog(@"%d", (int)self.navigationController.viewControllers.count);
[self.navigationController popToViewController:self.navigationController.viewControllers[2];

Answer 1

Your stack would have been removed as soon as you call popViewController: to check try this

[self.navigationController popToViewController:self.navigationController.viewControllers[2];
 double delayInSeconds = .1;
    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
    dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
NSLog(@"%d", (int)self.navigationController.viewControllers.count);
    });

instead of

NSLog(@"%d", (int)self.navigationController.viewControllers.count);
[self.navigationController popToViewController:self.navigationController.viewControllers[2];

Answer 2

You should log view controllers in the stack after you call popToViewController: method (In the code you provided you have NSLog method before you call popToViewController: method. Just try this code and see that "BEFORE POP" is larger than "AFTER POP".

NSLog(@"BEFORE POP: %d", (int)self.navigationController.viewControllers.count);
[self.navigationController popToRootViewControllerAnimated:YES];
NSLog(@"AFTER POP: %d", (int)self.navigationController.viewControllers.count);

popToViewController method will remove all viewController s which were added to the stack after the viewController you pass as a parameter. And it does not matter if you pass YES in popToRootViewControllerAnimated: , the stack will be updated right after you call this method before the animation is finished. Although the actual view controller object will probably be still retained until the animation is finished, but that's UINavigationController 's job, so do not worry about that.

Answer 3

[self.navigationController popToRootViewControllerAnimated:YES];

will update the stack contents after the pop animation is complete.

So assuming you have a hierarchy like this:

NavigationController RootViewController FirstViewController SecondViewController

your stack count should be 3

if you call [self.navigationController popToRootViewControllerAnimated:YES]; within any of the view controllers, at the end of the animation, your hierarchy should look like this:

NavigationController RootViewController

and you stack count should be 1

If this isn't the case, then perhaps you are somehow corrupting the stack in code we haven't seen yet.

Answer 4

Are you using ARC? If so, the popped view controllers will be automatically deallocated. If they are not deallocated then there are some variables which are retained by ARC. Take a look at your code and see if you have some strong references declared inside the view controllers.

For example, properties which are not IBOutlets causes ARC to retain them even when the view controllers are popped out from the navigation controller, and dealloc is never called on these view controllers. Transform these properties into private variables and then use public methods to access them.