How to change Back button text from within the child view controller? - ios

Question

I know that you can set the title of the back button from the IB or in prepareForSegue, but in my app I need to update the title according to events that can happen while the controller is visible.
I tried but nothing happens:
self.navigationItem.backBarButtonItem = UIBarButtonItem(title: title, style: .Plain, target: nil, action: nil)
This works though but has no back arrow:
self.navigationItem.leftBarButtonItem = UIBarButtonItem(title: title, style: .Plain, target: nil, action: "popVC")
Any ideas?

Answer 1

The backBarButtonItem is the item used for the back button of the next controller in the navigation stack.
So for example if you have a navigation controller with a root viewController A and you push a viewController B, then the back button title that you see once B is pushed is configured using A.
You could have something like this :
A.navigationItem.backBarButtonItem = UIBarButtonItem(title: "Go back to A", style: .Plain, target: nil, action: nil)
Once B is pushed, you see a back button with "Go back to A".
In your case the tricky part is to find A in the navigation stack from B.
You can do it by searching in the viewControllers of the navigationController like so :
// This code works from the `B` view controller
let viewControllers = self.navigationController?.viewControllers ?? []
if let indexOfCurrent = viewControllers.indexOf(self) where (indexOfCurrent > viewControllers.startIndex) {
let indexOfPrevious = indexOfCurrent.advancedBy(-1)
let previousViewController = viewControllers[indexOfPrevious]
previousViewController.navigationItem.backBarButtonItem?.title = "New Title"
}
Edit
I don't know any clean way to refresh the navigation bar after that. Maybe you could ask a separate question just for that.
What you could do is pop and push the view controller without animation
if let navigationController = self.navigationController {
navigationController.popViewControllerAnimated(false)
navigationController.pushViewController(self, animated: false)
}
Or maybe try to create a new UIBarButtonItem instead of changing the title of the existing one.

Answer 2

try this:
let baritems = self.navigationController?.navigationBar.items
for item in baritems!{
if (item.leftBarButtonItem != nil){
item.title = "123"
}
}

Answer 3

This question is pretty old now, but I was a problem changing the back button text based on a nested tableViewController's selected cell.
It looks like the default back button for a navigationViewController bases its text on the title of the view controller it takes the user back to.
You should probably be careful, as my solution makes a couple assumptions that I'm not positive will always be true.
let vcs = navigationController?.viewControllers
vcs?[(vcs?.count)! - 2].navigationItem.title = "Your Text Here"
Assuming that our current view controller is at the top of the navigation stack -> vcs[vcs.count - 1]; there exists a view controller on that stack before this one -> vcs[vcs.count - 2]; and the navigationItem.title of that preceding view controller can be changed without unwanted side effects; we can change our back button text by changing the navigation title of that preceding view controller.