How can I pop a view from a UINavigationController and replace it with another in one operation?

Matt_Brandt_7383 0
Viewed 80915

I have an application where I need to remove one view from the stack of a UINavigationController and replace it with another. The situation is that the first view creates an editable item and then replaces itself with an editor for the item. When I do the obvious solution within the first view:

MyEditViewController *mevc = [[MYEditViewController alloc] initWithGizmo: gizmo];

[self retain];
[self.navigationController popViewControllerAnimated: NO];
[self.navigationController pushViewController: mevc animated: YES];
[self release];

I get very strange behavior. Usually the editor view will appear, but if I try to use the back button on the nav bar I get extra screens, some blank, and some just screwed up. The title becomes random too. It is like the nav stack is completely hosed.

What would be a better approach to this problem?

Thanks, Matt

uinavigationcontroller uiviewanimation iphone cocoa-touch
16 Answers

From experience, you're going to have to fiddle with the UINavigationController's viewControllers property directly. Something like this should work:

MyEditViewController *mevc = [[MYEditViewController alloc] initWithGizmo: gizmo];

[[self retain] autorelease];
NSMutableArray *controllers = [[self.navigationController.viewControllers mutableCopy] autorelease];
[controllers removeLastObject];
self.navigationController.viewControllers = controllers;
[self.navigationController pushViewController:mevc animated: YES];

Note: I changed the retain/release to a retain/autorelease as that's just generally more robust - if an exception occurs between the retain/release you'll leak self, but autorelease takes care of that.

user_5820

After much effort (and tweaking the code from Kevin), I finally figured out how to do this in the view controller that is being popped from the stack. The problem that I was having was that self.navigationController was returning nil after I removed the last object from the controllers array. I think it was due to this line in the documentation for UIViewController on the instance method navigationController "Only returns a navigation controller if the view controller is in its stack."

I think that once the current view controller is removed from the stack, its navigationController method will return nil.

Here is the adjusted code that works:

UINavigationController *navController = self.navigationController;
MyEditViewController *mevc = [[MYEditViewController alloc] initWithGizmo: gizmo];

NSMutableArray *controllers = [[self.navigationController.viewControllers mutableCopy] autorelease];
[controllers removeLastObject];
navController.viewControllers = controllers;
[navController pushViewController:mevc animated: YES];
Admin1

This UINavigationController instance method might work...

Pops view controllers until the specified view controller is the top view controller and then updates the display.

- (NSArray *)popToViewController:(UIViewController *)viewController animated:(BOOL)animated
diclophis_326780
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