How do I show/hide a UIBarButtonItem?

Question

I created a toolbar in IB with several buttons. I would like to be able to hide/show one of the buttons depending on the state of the data in the main window.

Answer 1

You need to manipulate the toolbar.items array.

Here is some code I use to hide and display a Done button. If your button is on the extreme edge of the toolbar or in-between other buttons your other buttons will move, so if you want your button to just disappear then place your button as the last button towards the centre. I animate the button move for effect, I quite like it.

-(void)initLibraryToolbar {

    libraryToolbarDocumentManagementEnabled = [NSMutableArray   arrayWithCapacity:self.libraryToolbar.items.count];
    libraryToolbarDocumentManagementDisabled = [NSMutableArray arrayWithCapacity:self.libraryToolbar.items.count];
    [libraryToolbarDocumentManagementEnabled addObjectsFromArray:self.libraryToolbar.items];
    [libraryToolbarDocumentManagementDisabled addObjectsFromArray:self.libraryToolbar.items];
    trashCan = [libraryToolbarDocumentManagementDisabled objectAtIndex:3];
    mail = [libraryToolbarDocumentManagementDisabled objectAtIndex:5];
    [libraryToolbarDocumentManagementDisabled removeObjectAtIndex:1];
    trashCan.enabled = NO;
    mail.enabled = NO;
    [self.libraryToolbar setItems:libraryToolbarDocumentManagementDisabled animated:NO];

}

so now can use the following code to show your button

[self.libraryToolbar setItems:libraryToolbarDocumentManagementEnabled animated:YES];
trashCan.enabled = YES;
mail.enabled = YES; 

or to hide your button

[self.libraryToolbar setItems:libraryToolbarDocumentManagementDisabled animated:YES];
trashCan.enabled = NO;
mail.enabled = NO;