gist1.m

NSMutableArray* buttons = [NSMutableArray arrayWithCapacity:2];

gist2.m

// Add items to the array
UIBarButtonItem* bi;
bi = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd 
                                                   target:self 
                                                   action:@selector(barButtonClicked:)];
[buttons addObject:bi];
[bi release];
    
bi = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCamera 
                                                   target:self 
                                                   action:@selector(barButtonClicked:)];
[buttons addObject:bi];
[bi release];

gist3.m

// Create a Flexible Space to right align the buttons
bi = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace 
                                                   target:nil action:nil];
[buttons insertObject:bi atIndex:0];
[bi release];

gist4.m

// Create and configure the toolbar, with the items array
UIToolbar *toolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 103, 44.01)];
toolbar.autoresizingMask = UIViewAutoresizingFlexibleHeight;
toolbar.clearsContextBeforeDrawing = NO;
toolbar.tintColor = self.navigationController.navigationBar.tintColor;
toolbar.barStyle = -1; // Limpa o background

[toolbar setItems:buttons animated:NO];

gist5.m

// define a "container" button
self.navigationItem.rightBarButtonItem = [[[UIBarButtonItem alloc] initWithCustomView:toolbar] autorelease];

YourViewController.m

- (void)setupNavigationItems
{
    NSMutableArray* buttons = [NSMutableArray arrayWithCapacity:2];
    
    // Add items to the array
    UIBarButtonItem* bi;
    bi = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd 
                                                       target:self 
                                                       action:@selector(barButtonClicked:)];
    [buttons addObject:bi];
    [bi release];
    
    bi = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCamera 
                                                       target:self 
                                                       action:@selector(barButtonClicked:)];
    [buttons addObject:bi];
    [bi release];
    
    // Create a Flexible Space to right align the buttons
    bi = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace 
                                                       target:nil action:nil];
    [buttons insertObject:bi atIndex:0];
    [bi release];
    
    // Create and configure the toolbar, with the items array
    UIToolbar *toolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 103, 44.01)];
    toolbar.autoresizingMask = UIViewAutoresizingFlexibleHeight;
    toolbar.clearsContextBeforeDrawing = NO;
    toolbar.tintColor = self.navigationController.navigationBar.tintColor;
    toolbar.barStyle = -1; // Limpa o background
    
    [toolbar setItems:buttons animated:NO];

    // define a "container" button
    self.navigationItem.rightBarButtonItem = [[[UIBarButtonItem alloc] initWithCustomView:toolbar] autorelease];
    

    // This button was added so you can compare the "native" button and the toolbar buttons
    self.navigationItem.leftBarButtonItem = [[[UIBarButtonItem alloc] initWithTitle:@"Some Title" 
                                                                              style:UIBarButtonItemStyleBordered 
                                                                             target:self 
                                                                             action:@selector(barButtonClicked:)] autorelease];
    [toolbar release];
}