CODEWITHSUNDEEP
objective-ciosuiviewcontroller
OhDoh
OhDoh

Reputation: 433

Remove permanently UIViewController from the stack

Here is how I remove UIViewControllers which never will be used again in the app.

NSMutableArray *allViewControllers = [NSMutableArray arrayWithArray: self.navigationController.viewControllers];
    [allViewControllers removeObjectAtIndex:0];
    [allViewControllers removeObjectAtIndex:1];

  1. Is this the right way to remove view from the stack ?

  2. While running the app with Instruments I notice that the memory is not freed when the app enter the stage where the code above is executed. What is wrong here ?

Upvotes: 0

Views: 658

Answers (3)

Joel Kravets
Joel Kravets

Reputation: 2471

By assigning your view controllers into a new mutable array you increased their retain count by 1, removing them decreases their retain count by 1 so the net effect is zero. What you want to do is replace the view controllers that are part of the navigation controller after removing them, there by making the navigation controller release your old instances.

NSMutableArray *allViewControllers = [NSMutableArray arrayWithArray:self.navigationController.viewControllers];
[allViewControllers removeObjectAtIndex:0];
[allViewControllers removeObjectAtIndex:1];

[self.navigationController setViewControllers:allViewControllers animated:YES];

Upvotes: 0

zaph
zaph

Reputation: 112873

Creating a new NSMutableArray of the viewControllers and then removing from the new NSMutableArray accomplishes nothing. The viewControllers still are retain by the navigationController.

Upvotes: 3

Saurabh Passolia
Saurabh Passolia

Reputation: 8109

you are not actually freeing up the viewControllers. you are just increasing their retain count by +1 and then decreasing by -1.

actually nothing is getting affected by the code you have written to free your viewControllers.

For a NavigationController, you call popToRootViewController to release all other view controllers except the base/root viewcontroller for NavigationController.

Upvotes: 0

Related Questions