返回选项卡后自定义导航栏无法正确显示

Question

我在我正在创建的应用程序中向导航栏添加了一些组件。当您单击 URL 字段时，栏的高度会动态变化，就像在 iPhone 的 Safari 中一样。我的所有交互和大小调整都完美运行，除非我移动到另一个选项卡并返回。

如果我启动应用程序，请单击导航栏正确显示的第二个选项卡。

如果我然后立即单击第一个选项卡，然后再次返回第二个选项卡，导航栏被剪切。

我' m 在 vi​​ewWillAppear 方法中自定义导航栏

- (void)viewWillAppear:(BOOL)animated {

    [super viewWillAppear:animated];

    if (navBar == nil) {

        CGFloat width = self.view.frame.size.width;


        navBar = [self.navigationController.navigationBar autorelease];
        navBar.frame = CGRectMake(0,20,width,52);
        //This doesn't appear to have any effect- was set to           
        //UIViewAutoresizingFlexibleWidth and worked but with with the same issue.
        navBar.autoresizingMask = UIViewAutoresizingFlexibleHeight;

        self.navigationItem.title = nil;


        label = [[UILabel alloc] initWithFrame:
             CGRectMake(10,2,width-20,14)];     
        label.autoresizingMask = UIViewAutoresizingFlexibleWidth;
        label.text = @"My Custom NavBar";
        label.backgroundColor = [UIColor clearColor];
        label.font = [UIFont systemFontOfSize:12];
        label.textAlignment = UITextAlignmentCenter;
        [navBar addSubview:label];

        urlTextField = [[UITextField alloc] initWithFrame:
                    CGRectMake(10,19,width-75,26)]; 
        urlTextField.clearButtonMode = UITextFieldViewModeWhileEditing;
        [urlTextField addTarget:(id)self action:@selector(textFieldDidChange:) 
                                        forControlEvents:UIControlEventEditingChanged];


        bookmarkButton = [UIButton buttonWithType:UIButtonTypeCustom];
        bookmarkButton.frame = CGRectMake(0,0,21,21);
        [bookmarkButton setImage:[UIImage imageNamed:@"bookmark.png"] forState:UIControlStateNormal];
        [bookmarkButton addTarget:self action:@selector(bookmarkPressed:) forControlEvents:UIControlEventTouchUpInside];
        urlTextField.leftView = bookmarkButton;
        urlTextField.leftViewMode = UITextFieldViewModeAlways;


        actionButton = [UIButton buttonWithType:UIButtonTypeCustom];
        actionButton.frame = CGRectMake(0,0,21,21);
        [actionButton setImage:[UIImage imageNamed:@"refresh.png"] forState:UIControlStateNormal];
        [actionButton addTarget:self action:@selector(actionPressed:) forControlEvents:UIControlEventTouchUpInside];
        urlTextField.rightView = actionButton;
        urlTextField.rightViewMode = UITextFieldViewModeAlways;


        urlTextField.autoresizingMask = UIViewAutoresizingFlexibleWidth;
        urlTextField.borderStyle = UITextBorderStyleRoundedRect;
        urlTextField.font = [UIFont systemFontOfSize:17];
        urlTextField.delegate = self;
        [navBar addSubview:urlTextField];


    } else {

        //XXX This does make the navBar display correctly
        //but I don't really want the keyboard visible when returning from another tab
        //[urlTextField  becomeFirstResponder];

    }

}

请注意上面代码中的最后注释 - 如果我强制显示键盘，或者如果用户在 UITextField 中单击，则导航栏将从其中正确显示。

我已经尝试了很多方法 - 检查视图（图像中的视图 2）、导航栏的帧大小，但没有成功。有谁知道问题可能是什么？我很乐意提供更多细节。

谢谢。

Answer 1

基本上你的处理方式都是错误的。您永远不应该访问导航栏的框架（更不用说更改它），并且您当然不应该直接向其添加子视图。来自文档：

与其他类型的视图不同，您可以
不将子视图添加到导航栏
直接地。相反，您使用
导航项（一个实例
UINavigationItem 类）来指定
您想要什么按钮或自定义视图
显示。

因此，在视图控制器的 -(id)initWithNibName:bundle: 方法中，您需要：

// Setting this will automatically grow the height of the navigation bar
// to the appropriate height
self.navigationItem.prompt = @"My Custom NavBar";

// Construct urlTextField here ...
self.navigationItem.titleView = urlTextField;

// This is the button with the gears icon
UIBarButtomItem *rightButtonItem = [[UIBarButtomItem alloc] initWithCustomView:view];
self.navigationItem.rightBarButtonItem = rightButtomItem;
[rightButtomItem release];