ios - 将 UIBarButtonItem 添加到推送到 UINavigation Controller 上的 UIViewController

Question

我正在尝试将 UIViewController 推送到导航 Controller ，然后将 UIBarButtonItem 添加到导航栏，以便我可以使用它来显示倒数计时器。

UINavigationController *navController = [[Session sharedInstance] getNavigationController];
GamePlayViewController *gameController = [[GamePlayViewController alloc] initWithNibName:@"GamePlayViewController" bundle:nil ];

UIBarButtonItem *timerBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];

gameController.navigationItem.rightBarButtonItems = [NSArray arrayWithObjects:timerBtn, nil];

[navController pushViewController:gameController animated:YES];

当我使用上面的代码时，它不起作用。我也尝试从 Controller 本身的 ViewDidload 方法执行此操作，但没有骰子。我什至尝试使用 rightBarButtonItem 但收到错误消息

 "to uncaught exception 'NSInvalidArgumentException', reason: 'Fixed and flexible space   items not allowed as individual navigation bar button item. Please use the leftBarButtonItems (that's plural) property.'
*** First throw call stack:"




UIBarButtonItem *timerBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];

self.navigationItem.rightBarButtonItem = timerBtn;

Answer 1

如果您转到 IB 并尝试添加一个 Flexible Space 或 Fixed Space，您将看到这 2 个对象的详细信息，表明这 2 个对象只能添加到正在添加到 UIToolBar 的 UIBarButtonItem，而不能到导航栏!

所以我建议您将代码更改为以下内容:

UIBarButtonItem *timerBtn = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonItemStylePlain target:nil action:nil];