UIBarButtonItem changing title not working

问题:

How can I change the title of a UIBarButtonItem? I have the following code which is called when an "edit" button is pressed on my UINavigationBar.

-(void)editButtonSelected:(id)sender {
    NSLog(@"edit button selected!");
    if(editing) {
        NSLog(@"notediting");
        [super setEditing:NO animated:NO];
        [tableView setEditing:NO animated:NO];
        [tableView reloadData];
        [rightButtonItem setTitle:@"Edit"];
        [rightButtonItem setStyle:UIBarButtonItemStylePlain];
        editing = false;
    }
    else {
        NSLog(@"editing");
        [super setEditing:YES animated:YES];
        [tableView setEditing:YES animated:YES];
        [tableView reloadData];
        [rightButtonItem setTitle:@"Done"];
        [rightButtonItem setStyle:UIBarButtonItemStyleDone];
        editing = true;
    }
}

The "edit" button is changing color (so the line which sets the style is working), however the line which sets the title of the button is not working.

回答1:

I've done the following to dynamically change the title of a UIBarButtonItem. In this situation I am not using a UIViewTableController and cannot use the standard editButton. I have a view with a tableView as well as other subviews and wanted to emulate the behavior of the limited UIViewTableController.

- (void)InitializeNavigationItem
{
    NSMutableArray *array = [[NSMutableArray alloc] initWithCapacity:2];
    UIBarButtonItem* barButton;

    barButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd 
                                                              target:self 
                                                              action:@selector(addNewItem:)];
    barButton.style = UIBarButtonItemStyleBordered;
    [array addObject:barButton];

    // --------------------------------------------------------------------------------------

    barButton = [[UIBarButtonItem alloc] initWithTitle:@"Edit" style:UIBarButtonItemStyleBordered
                                                              target:self 
                                                              action:@selector(editMode:)];
    barButton.style = UIBarButtonItemStyleBordered;
    barButton.possibleTitles = [NSSet setWithObjects:@"Edit", @"Done", nil];
    [array addObject:barButton];

    self.navigationItem.rightBarButtonItems = array;
}

- (IBAction)editMode:(UIBarButtonItem *)sender
{
    if (self.orderTable.editing)
    {
        sender.title = @"Edit";
        [self.orderTable setEditing:NO animated:YES];
    }
    else
    {
        sender.title = @"Done";
        [self.orderTable setEditing:YES animated:YES];
    }
}

Note that I didn't use the the UIBarButtonSystemItemEdit barButton, you cannot manually change the name of that button, which makes sense.

You also might want to take advantage of the possibleTitles property so that the button doesn't resize when you change the title.

If you are using a Storyboard/XIB to create/set these buttons, ensure that the Bar Button Item Identifier is set to Custom for the button which you'd want to control the title for.

回答2:

I had this problem and resolved it by setting the UIBarButtonItem style to the custom type when it's initialised. Then the titles would set when changing their title values.

You may also want to set the possibleTitle value in the viewDidLoad method to ensure the button is sized correctly for all the possible titles it can have.

回答3:

If you look at the documentation of the title property, it is explicitly mentioned that you should set it before assigning it to the navigation bar. Instead of doing what you're doing right now, you can use two bar button items – one for done and one for edit, and set them alternatively.

回答4:

In my case what prevented the title being displayed was that in the xib I'd selected the Bar button item 'identifier' property as 'Cancel'.

I tried setting the title property even before assigning the button to the navigation bar, but the title was not being updated.

I made it like this:

And it started working just as I wanted.

回答5:

Actually if all you want if switching between "Edit" and "Done", just use self.navigationItem.rightBarButtonItem = self.editButtonItem;

It will handle this transition for you

回答6:

Just switch out the buttons each time the user presses them.

- (void)setNavigationButtonAsEdit
{
    UIBarButtonItem* editButton = [[UIBarButtonItem alloc] initWithTitle:NSLocalizedString(@"Edit", @"")
                                                                   style:UIBarButtonItemStylePlain
                                                                  target:self
                                                                  action:@selector(editButtonPressed:)];

    self.navigationItem.rightBarButtonItems = [NSArray arrayWithObject:editButton];
}

- (void)setNavigationButtonAsDone
{
    UIBarButtonItem* doneButton = [[UIBarButtonItem alloc] initWithTitle:NSLocalizedString(@"Done", @"")
                                                                   style:UIBarButtonItemStylePlain
                                                                  target:self
                                                                  action:@selector(editButtonPressed:)];
    self.navigationItem.rightBarButtonItems = [NSArray arrayWithObject:doneButton];
}

And then create an IBAction to handle the button press:

- (IBAction)editButtonPressed:(id)sender
{
    NSString* buttonText = [sender title];
    if ([buttonText isEqualToString:NSLocalizedString(@"Edit",@"")])
    {
        [self setNavigationButtonAsDone];
    }
    else
    {
        [self setNavigationButtonAsEdit];
    }
}

回答7:

Swift 3.0, 3.2, or 4.0

If your custom ViewController containing a tableView object follows the UITableViewController Delegate and Datasource protocols, you can append a system editBarButtonItem to your navigationItem.leftBarButtonItem(s) or navigationItem.rightBarButtonItem(s) with the following code:

func setupTableView() {
    tableView.delegate = self
    tableView.dataSource = self
    navigationItem.rightBarButtonItem = editButtonItem
    editButtonItem.action = #selector(CustomViewController.editTableView(_:))

}

@objc func editTableView(_ sender: UIBarButtonItem) {
    tableView.isEditing = !tableView.isEditing
    if tableView.isEditing {
        sender.title = "Done"
    } else {
        sender.title = "Edit"
    }
}

回答8:

Try:

UIButton *rightButton;
rightButton = (UIButton*)self.navigationItem.rightBarButtonItem.customView;
[rightButton setTitle:@"Done" forState:UIControlStateNormal];

Because rightBarButtonItem.customView == “the button your added”.