UINavigationController rightbarbuttonitem没有显示

Question

在完成与 UINavigationController 项目相关的问题后，我来发布我的确切问题.. 首先我没有在MainWindow.xib 中添加 UINavigationController 我创建并在AppDelegate 文件中添加 UINavigationController 之后在UIViewController（不在rootViewController）类中，我必须添加一个Done类型的右栏按钮我是 将其添加到 searchbarDelegate 方法中，显示为粗体：-

- (void) searchBarTextDidBeginEditing:(UISearchBar *)theSearchBar {

//This method is called again when the user clicks back from teh detail view.
//So the overlay is displayed on the results, which is something we do not want to happen.

if(exhibDataObj.searching)
    return;

//Add the overlay view.
if(ovController == nil)
    ovController = [[OverlayViewController alloc] initWithNibName:@"OverlayView" bundle:[NSBundle mainBundle]];

CGFloat yaxis = self.navigationController.navigationBar.frame.size.height;
CGFloat width = self.view.frame.size.width;
CGFloat height = self.view.frame.size.height;

//Parameters x = origion on x-axis, y = origon on y-axis.
CGRect frame = CGRectMake(0, yaxis, width, height);
ovController.view.frame = frame;    
ovController.view.backgroundColor = [UIColor grayColor];
ovController.view.alpha = 0.5;

ovController.rvController = self;

[self.theTableView insertSubview:ovController.view aboveSubview:self.parentViewController.view];

exhibDataObj.searching = true;
letUserSelectRow = NO;
self.theTableView.scrollEnabled = NO;

//Add the done button.
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] 
                                          initWithBarButtonSystemItem:UIBarButtonSystemItemDone 
                                          target:self action:@selector(doneSearching_Clicked:)];
 }

但这永远行不通。

任何帮助都会更有意义。

Answer 1

我已经快速测试了您的代码，它似乎对我来说工作正常，但是，我曾经遇到过同样的问题，后来发现我在设置它后在 viewDidLoad 方法中将 rightBarButtonItem 设置为 nil到一个按钮。你应该确保你不会以某种方式犯同样的错误。

但是，如果这对您不起作用，您可以随时尝试为其设置自定义按钮：

UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(0, 5, 30, 30)];

button.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@"done.png"]];

[button addTarget:self action:@selector(doneButtonClicked) forControlEvents:UIControlEventTouchUpInside];

UIBarButtonItem *customItem = [[UIBarButtonItem alloc] initWithCustomView:button];

self.navigationController.visibleViewController.navigationItem.rightBarButtonItem = customItem;