iPhone仅在第一页上隐藏导航栏

Question

我有下面的代码隐藏并显示导航栏.它在第一个视图加载时隐藏,然后在调用"children"时隐藏.麻烦的是,当他们回到根视图时,我找不到触发它再次隐藏的事件/动作....

我在根页面上有一个"测试"按钮,用于手动执行操作,但它并不漂亮,我希望它是自动的.

-(void)hideBar 
{
    self.navController.navigationBarHidden = YES;
}
-(void)showBar 
{       
    self.navController.navigationBarHidden = NO;
}

Answer 1

我发现最好的解决方案是在第一个视图控制器中执行以下操作.

Objective-C的

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

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

迅速

override func viewWillAppear(animated: Bool) {
    self.navigationController?.setNavigationBarHidden(true, animated: animated)
    super.viewWillAppear(animated)
}

override func viewWillDisappear(animated: Bool) {
    self.navigationController?.setNavigationBarHidden(false, animated: animated)
    super.viewWillDisappear(animated)
} 

这将导致导航栏从左边(下一个视图一起),动画,当你推下一个UIViewController堆栈上,和(同旧观点一起)动画至左侧,当你按后退按钮UINavigationBar.

请注意,这些不是委托方法,您要覆盖UIViewController这些方法的实现,并且根据文档,您必须在实现中的某处调用super的实现.

Answer 2

我找到的另一种方法是为以下方面设置委托NavigationController:

navigationController.delegate = self;

并使用setNavigationBarHidden在navigationController:willShowViewController:animated:

- (void)navigationController:(UINavigationController *)navigationController 
      willShowViewController:(UIViewController *)viewController 
                    animated:(BOOL)animated 
{   
    // Hide the nav bar if going home.
    BOOL hide = viewController != homeViewController;
    [navigationController setNavigationBarHidden:hide animated:animated];
}

ViewController在一个地方轻松自定义每个人的行为.

Answer 3

我必须对其他答案进行一些轻微的调整,只是取消隐藏在viewWillDisappear中的栏,如果它消失的原因是由于推送它的导航项目.这是因为视图可能因其他原因而消失.

所以如果这个视图不再是最顶层的视图,我只会取消隐藏栏:

- (void) viewWillDisappear:(BOOL)animated
{
    if (self.navigationController.topViewController != self)
    {
        [self.navigationController setNavigationBarHidden:NO animated:animated];
    }

    [super viewWillDisappear:animated];
}

Answer 4

我会将代码放在viewWillAppear委托中,显示每个视图:

像这样你需要隐藏它:

- (void)viewWillAppear:(BOOL)animated
{
        [yourObject hideBar];
}

像这样你需要展示它:

- (void)viewWillAppear:(BOOL)animated
{
        [yourObject showBar];
}

Answer 5

当前接受的答案与问题中描述的预期行为不匹配.该问题要求导航栏隐藏在根视图控制器上,但在其他任何地方都可见,但接受的答案会隐藏特定视图控制器上的导航栏.当第一个视图控制器的另一个实例被推入堆栈时会发生什么？即使我们没有查看根视图控制器,它也会隐藏导航栏.

相反,@ Chad M.的使用策略UINavigationControllerDelegate是一个很好的策略,这是一个更完整的解决方案.脚步:

1. 子类 UINavigationController
2. 实现-navigationController:willShowViewController:animated方法以显示或隐藏导航栏是否显示根视图控制器
3. 重写初始化方法以将UINavigationController子类设置为其自己的委托

此解决方案的完整代码可在此Gist中找到.这是navigationController:willShowViewController:animated实施:

- (void)navigationController:(UINavigationController *)navigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    /* Hide navigation bar if root controller */
    if ([viewController isEqual:[self.viewControllers firstObject]]) {
        [self setNavigationBarHidden:YES animated:animated];
    } else {
        [self setNavigationBarHidden:NO animated:animated];
    }
}

Answer 6

在Swift 3中:

override func viewWillAppear(_ animated: Bool) {
    navigationController?.navigationBar.isHidden = true
    super.viewWillAppear(animated)
}


override func viewWillDisappear(_ animated: Bool) {
    if (navigationController?.topViewController != self) {
        navigationController?.navigationBar.isHidden = false
    }
    super.viewWillDisappear(animated)
}

Answer 7

感谢@chad-m 的回答。

这是 Swift 版本：

1. 创建一个新文件 MyNavigationController.swift

import UIKit

class MyNavigationController: UINavigationController, UINavigationControllerDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        self.delegate = self
    }

    func navigationController(_ navigationController: UINavigationController, willShow viewController: UIViewController, animated: Bool) {
        if viewController == self.viewControllers.first {
            self.setNavigationBarHidden(true, animated: animated)
        } else {
            self.setNavigationBarHidden(false, animated: animated)
        }
    }

}

2. 将 StoryBoard 中的 UINavigationController 类设置为 MyNavigationController 就是这样！

chad-m 的答案和我的答案之间的区别：

1. 继承自UINavigationController，所以不会污染你的rootViewController。

2. 使用self.viewControllers.first而不是homeViewController，因此您不会为 1 个 StoryBoard 中的 100 个 UINavigationController 执行 100 次此操作。

Answer 8

经过多次试验,我是如何让它按照我想要的方式工作的.这就是我的尝试. - 我有一个图像的视图.我想让图像全屏显示. - 我也有一个带tabBar的导航控制器.所以我也需要隐藏它. - 此外,我的主要要求不仅仅是隐藏,而是在显示和隐藏时也有褪色效果.

这就是我的工作方式.

第1步 - 我有一个图像,用户点击该图像一次.我抓住那个手势并将其推入新的imageViewController,它在imageViewController,我希望有全屏图像.

- (void)handleSingleTap:(UIGestureRecognizer *)gestureRecognizer {  
NSLog(@"Single tap");
ImageViewController *imageViewController =
[[ImageViewController alloc] initWithNibName:@"ImageViewController" bundle:nil];

godImageViewController.imgName  = // pass the image.
godImageViewController.hidesBottomBarWhenPushed=YES;// This is important to note. 

[self.navigationController pushViewController:godImageViewController animated:YES];
// If I remove the line below, then I get this error. [CALayer retain]: message sent to deallocated instance . 
// [godImageViewController release];
} 

第2步 - 以下所有这些步骤都在ImageViewController中

步骤2.1 - 在ViewDidLoad中,显示navBar

- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
NSLog(@"viewDidLoad");
[[self navigationController] setNavigationBarHidden:NO animated:YES];
}

步骤2.2 - 在viewDidAppear,设置延迟定时器任务(我将其设置为1秒延迟).并且在延迟之后,添加褪色效果.我使用alpha来使用淡入淡出.

- (void)viewDidAppear:(BOOL)animated
{
NSLog(@"viewDidAppear");

myTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self     selector:@selector(fadeScreen) userInfo:nil repeats:NO];
}

- (void)fadeScreen
{
[UIView beginAnimations:nil context:nil]; // begins animation block
[UIView setAnimationDuration:1.95];        // sets animation duration
self.navigationController.navigationBar.alpha = 0.0;       // Fades the alpha channel of   this view to "0.0" over the animationDuration of "0.75" seconds
[UIView commitAnimations];   // commits the animation block.  This Block is done.
}

步骤2.3 - 在viewWillAppear,将singleTap手势添加到图像并使navBar半透明.

- (void) viewWillAppear:(BOOL)animated
{

NSLog(@"viewWillAppear");


NSString *path = [[NSBundle mainBundle] pathForResource:self.imgName ofType:@"png"];

UIImage *theImage = [UIImage imageWithContentsOfFile:path];

self.imgView.image = theImage;

// add tap gestures 
UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTap:)];  
[self.imgView addGestureRecognizer:singleTap];  
[singleTap release];  

// to make the image go full screen
self.navigationController.navigationBar.translucent=YES;
}

- (void)handleTap:(UIGestureRecognizer *)gestureRecognizer 
{ 
 NSLog(@"Handle Single tap");
 [self finishedFading];
  // fade again. You can choose to skip this can add a bool, if you want to fade again when user taps again. 
 myTimer = [NSTimer scheduledTimerWithTimeInterval:5.0 target:self  selector:@selector(fadeScreen) userInfo:nil repeats:NO];
 }

第3步 - 最后viewWillDisappear,确保将所有东西都放回原处

- (void)viewWillDisappear: (BOOL)animated 
{ 
self.hidesBottomBarWhenPushed = NO; 
self.navigationController.navigationBar.translucent=NO;

if (self.navigationController.topViewController != self)
{
    [self.navigationController setNavigationBarHidden:NO animated:animated];
}

[super viewWillDisappear:animated];
}