UIToolbar not showing UIBarButtonItem

问题

I'm using a storyboard and I've a split view where the master is a UITableViewController. Like the iPad Mail app, I'd like to display a UIToolbar.

I wasn't able to add the toolbar via storyboard but I managed to add it programmatically. I'm also able to add a UILabel to the toolbar, but I can't find a way to add a refresh button or any kind of UIBarButtonItem.

Any idea?

- (void)viewDidLoad {
  [super viewDidLoad];

  [self.navigationController setToolbarHidden:NO];

  UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(50.0f, 0.0f, 80.0f, 40.0f)];
  label.text = @"last updated...";
  label.textAlignment = UITextAlignmentCenter;
  label.font = [UIFont systemFontOfSize:13.0];
  [self.navigationController.toolbar addSubview:label];

  UIBarButtonItem *item1 = [[UIBarButtonItem alloc] initWithTitle:@"Item" style:UIBarButtonItemStylePlain target:self action:@selector(action:)];
  UIBarButtonItem *item2 = [[UIBarButtonItem alloc] initWithTitle:@"Item1" style:UIBarButtonItemStyleBordered target:self action:@selector(action:)];

  NSArray *buttons = @[item1, item2, nil];
  [self.navigationController.toolbar setItems:buttons animated:NO];

回答1:

Found the answer thanks to the Apple iOS Forum!

When you use the toolbar of the navigation controller, you have to set the toolbar buttons on the active view controller's toolbarItems property, not on the actual navigation controller's toolbar itself.

From the UINavigationController docs:

Displaying a Toolbar

A navigation controller object manages an optional toolbar in its view hierarchy. When displayed, this toolbar obtains its current set of items from the toolbarItems property of the active view controller. When the active view controller changes, the navigation controller updates the toolbar items to match the new view controller, animating the new items into position when appropriate.

For example:

[self setToolbarItems:buttons animated:NO];

来源：https://stackoverflow.com/questions/10825572/uitoolbar-not-showing-uibarbuttonitem