对象C：视图出现后出现导航栏按钮

Question

我有一个信息按钮，作为我UIImagePickerController的自定义叠加层的一部分。当您单击它时，我设置导航栏的外观（在UIImagePickerController＆＃34;演示文稿＆＃34;中隐藏）并推送新的视图控制器：

- (IBAction)infoButtonPressed:(id)sender {
    CameraHelpViewController *helpController = [[[CameraHelpViewController alloc] initWithNibName:@"CameraHelpViewController" bundle:nil] autorelease];

    [[UINavigationBar appearance] setBarStyle:UIBarStyleBlackTranslucent];
    [[UINavigationBar appearance] setBarTintColor:[UIColor blackColor]];
    [[UINavigationBar appearance] setTranslucent:NO];
    [ipc pushViewController:helpController animated:NO];

}

CameraHelpViewController.m

- (void)viewDidLoad {
    [super viewDidLoad];

    // Web view loading
    NSString *basePath = [[NSBundle mainBundle] resourcePath];
    basePath = [basePath stringByReplacingOccurrencesOfString:@"/" withString:@"//"];
    basePath = [basePath stringByReplacingOccurrencesOfString:@" " withString:@"%20"];      
    NSString *HTMLfile =[[NSBundle mainBundle] pathForResource:@"camera_help" ofType:@"html"];
    NSError *error;
    NSString *stringFromPath = [[[NSString alloc] initWithContentsOfFile:HTMLfile encoding:NSUTF8StringEncoding error:&error] autorelease];     

    [webView loadHTMLString:stringFromPath baseURL:[NSURL URLWithString:[NSString stringWithFormat:@"file:/%@//", basePath]]];
    webView.backgroundColor = [UIColor blackColor];     
    webView.opaque = NO; // Prevents the white flash from occurring     
    [_activityIndicator startAnimating];
}

//UPDATE:
- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [self.navigationController setNavigationBarHidden:NO animated:animated];
}

- (void)viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];
    [self.navigationController setNavigationBarHidden:YES animated:animated];
}

更新，因为使用@ryancrunchi中的代码，导航栏按钮不会移动到视图中。相反，导航栏在视图加载后向上移动几秒钟。

我希望在新视图出现之前完全设置导航栏。我怎么能这样做？

Answer 1

使用以下行： [ipc setNavigationBarHidden:NO animated:YES]; [ipc pushViewController:helpController animated:NO]; 您正在为导航栏设置动画，但是在没有动画的情况下显示helpController。因此helpController出现在导航栏之前，导航栏本身正在播放动画（延迟显示）。 如果您根本不想要动画，请将[ipc setNavigationBarHidden:NO animated:NO];放在CameraHelpViewController：

中

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    [ipc setNavigationBarHidden:NO animated:animated];
    // or
    [self.navigationController setNavigationBarHidden:NO animated:animated];
}

并在视图消失时隐藏栏：

- (void)viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];
    [ipc setNavigationBarHidden:YES animated:animated];
    // or
    [self.navigationController setNavigationBarHidden:YES animated:animated];
}