将 UIBarButtonItems 添加到工具栏时出现问题

我有一个 UINavigationController 和一个 UITableViewController 。我想在底部显示一个带有 UIBarButtonItem 的工具栏。工具栏已显示，但按钮不会出现。有人知道为什么吗？

  - (void)viewDidLoad {
        [super viewDidLoad];
     [[self navigationItem] setTitle:@"Selections List"];
     [[self navigationItem] setRightBarButtonItem:[[[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(addProjectSearch:)] autorelease]];
        [[self navigationItem] setLeftBarButtonItem:[self editButtonItem]];
     [[super tableView] setDataSource: self];
     [[super tableView] setDelegate: self];

     //Toolbar 
     UIBarButtonItem * logoutButton = [[[UIBarButtonItem alloc] initWithTitle:@"Log out" style:UIBarButtonItemStylePlain target:self action:@selector(logOut:)]autorelease];
     NSMutableArray * arr = [NSMutableArray arrayWithObjects:logoutButton, nil];
     [[self navigationController] setToolbarHidden: NO animated:YES];
     [[self navigationController] setToolbarItems:arr animated:YES]; 
    }

替换这一行：

[[self navigationController] setToolbarItems:arr animated:YES];

有了这个：

[self setToolbarItems:arr animated:YES];

一般来说，您应该设置toolbarItems在您推送的每个单独的视图控制器上，而不是在 UINavigationController 本身上。