导航控制器中的backBarButtonItem未显示

Question

我从NavigationViewController模板开始我的xcode项目.现在,当我按下视图时,该视图默认情况下会出现一个编辑按钮而没有后退按钮.我已经注释掉editButton代码和相应的setEditing委托方法.但是我无法显示后退按钮.我究竟做错了什么？

推动新视图:

PlaylistViewController *playlistViewController = [[PlaylistViewController alloc] init];
playlistViewController.managedObjectContext = self.managedObjectContext;

[self.navigationController pushViewController:playlistViewController animated:YES];
[playlistViewController release];

在我的PlaylistViewController中:

- (void)viewDidLoad {
    [super viewDidLoad];

    self.title = @"";

    // self.navigationItem.leftBarButtonItem = self.editButtonItem;

    // doesn't matter if this is here or not
    self.navigationItem.hidesBackButton = false;

    UIBarButtonItem *addButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:@selector(insertNewObject)];
    self.navigationItem.rightBarButtonItem = addButton;
    [addButton release];
}

Answer 1

当你告诉UINavigationController pushViewController时,它会自动将navigationItem.leftBarButtonItem设置为一个带有前一个UIViewController标题标题的按钮.

如果未设置标题,则默认文本为"返回".

如果标题设置为"",则根本不会显示任何按钮.

self.title = @"";

尝试更改此文本,后退按钮应与此处设置的文本相匹配.

或者,您可以从新的UIViewController 手动覆盖leftBarButtonItem的文本.