Changing UIBarButtonItem Identifier programatically

**mr-sk** · 06-29-2009, 04:29 PM

Hello,

So, I've searched around and looked through the class reference, but I cannot find the answer. I'm trying to change a UIBarButtonItem's Identifier, from 'Add' (+) to Undo once selected.

Code:

- (IBAction)addToFav:(id)sender
{    
    NSLog(@"Add Button Pressed");    
    addButton.enabled = FALSE;
    //addButton.style = UIBarButtonSystemItemUndo;
    UIBarButtonItem *newUndoButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemUndo target:self action:@selector(id)];
    self.navigationItem.rightBarButtonItem = newUndoButton;

Disabling the button works fine, but what I really want to do is replace it with a Undo button. The above code doesn't work ...

How should I do this?

Thanks in advance -
- sk

Avocado · 06-29-2009, 05:06 PM

I'm by no means a guru at iPhone development yet, but "action:@selector(id)" looks troublesome to me.

Don't you need to put a method signature there?

Maybe give that a whirl?

Avocado · 06-29-2009, 05:14 PM

Also, won't you be leaking if you don't release the Add button?

**mr-sk** · 06-29-2009, 05:20 PM

Avocado - Hey, yeah, I wasn't sure what to put for the @selector ... so, say I just do this instead:

Code:

    UIBarButtonItem *newUndoButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemUndo target:self action:@selector(addToFav)];

Still doesn't work ..

As for the leak, yeah I should release in dealloc.

Avocado · 06-29-2009, 05:25 PM

you need a colon after addToFav, since the method signature is - (IBAction)addToFav

id)sender

...action:@selector(addToFav

];

Hopefully that works.

**mr-sk** · 06-29-2009, 05:29 PM

That doesn't seem to fix it (woah I'm sloppy w/the code today) heh.

Avocado · 06-29-2009, 05:33 PM

Damn...I thought that would do it.

When you figure it out, would you mind posting here? I'd be interested to see what was wrong.

Thanks

**mr-sk** · 06-29-2009, 05:43 PM

Sure thing - I'll keep digging and report back.

Artem · 06-30-2009, 03:08 AM

It works for me:

Code:

[self.navigationItem setRightBarButtonItem:currentRightBarButton];

Also, I noticed that sometimes rightBarButtonItem doesn't get changed for some reason. So I added:

Code:

[self.navigationItem setRightBarButtonItem:nil];
[self.navigationItem setRightBarButtonItem:currentRightBarButton];
[self.rootController.tabBarController.view setNeedsDisplay];

This works well.

**mr-sk** · 06-30-2009, 08:08 PM

Hey Artem & Avocado -

Probably the fact I'm still learning that I'm totally making this a bigger problem than it should be here:

Here's the method that I'm trying to change the UIBarButton in:

Code:

- (IBAction)addToFav:(id)sender
{    
    NSLog(@"Add Button Pressed");    
    addButton.enabled = FALSE;

     ....HERE....

    [self insertIntoDB:[NSString stringWithFormat:@"..."]];
}

Currently, I'm just setting the add button to disabled. But what I want to do is make it (create in its place, etc) an 'Undo' button. If they select the 'Undo' button, it should then go back to an 'Add' button.

Also, here's a picture of the controller I'm working with:

http://mr-sk.com/iphone/controller.png

Thanks - much appreciated.
- sk

**EDIT** Artem, I tried what you mentioned, but could not get it to work. I think its an issue with me being confused on exactly the syntax/names of the controllers VS what you've provided...any assistance is greatly appreciated.

**mr-sk** · 07-01-2009, 02:24 PM

Still fighting this - bump.

Artem · 07-02-2009, 01:07 AM

Quote:

Artem, I tried what you mentioned, but could not get it to work. I think its an issue with me being confused on exactly the syntax/names of the controllers VS what you've provided...any assistance is greatly appreciated.

Yeah, sorry for confusion. You need to do something like this:

Code:

[self.navigationItem setRightBarButtonItem:nil];
[self.navigationItem setRightBarButtonItem:currentRightBarButton];

EITHER::[self.view setNeedsDisplay];
OR:::::::[self.tabBarController.view setNeedsDisplay]

..'self' here is navigation controller instance.

**mr-sk** · 07-02-2009, 07:46 PM

Quote:

Originally Posted by Artem

Yeah, sorry for confusion. You need to do something like this:

Code:

[self.navigationItem setRightBarButtonItem:nil];
[self.navigationItem setRightBarButtonItem:currentRightBarButton];

EITHER::[self.view setNeedsDisplay];
OR:::::::[self.tabBarController.view setNeedsDisplay]

..'self' here is navigation controller instance.

Hey, ok, but I dont have a navigation controller. Checkout this image so you can see my IB/nib structure: http://mr-sk.com/iphone/controller.png

What's highlighted in the screen shot is the item I'm trying to change. The code you provided doesn't work on what I have.

Thanks for the help this far - I think we're close.

- sk

**mr-sk** · 07-02-2009, 09:38 PM

So, I kinda got this working - Not totally happy with it, but it works.

I set the UIBarButtonItem to 'Custom', so that allows me to change the title programmatically (as I understand it):

Code:

    if ([addButton.title isEqualToString:@"Remove"])
    {
        addButton.title = @"Add";
    }
    else
    {
        addButton.title = @"Remove";  
    }

That works fine. Still doesn't solve my original problem, but at least I can now move onto something else.

Thanks for the help.

- sk