运行构建时 UINavigationController 未显示

Question

编辑：工作，请参阅下面的代码。

正在开发一个应用程序，现在我有 AppDelegate 类和自定义 UINavigationController 类。我现在的代码非常简单，我觉得我已经正确设置了 XIB 。构建成功，没有错误。但是当应用程序启动时，导航控制器不会显示。我没有看到导航栏，也没有看到表格视图。我所看到的只是一个空白屏幕。这是我的大部分代码：

//
//  FTPPhotosAppDelegate.h
//  FTPPhotos
//
//  Created by Aaron McLeod on 11-05-30.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import <UIKit/UIKit.h>
#import "RootViewController.h"

@interface FTPPhotosAppDelegate : NSObject <UIApplicationDelegate> {
    UINavigationController *navigationController;
    RootViewController *rootViewController;
}

@property (nonatomic, retain) UINavigationController *navigationController;
@property (nonatomic, retain) IBOutlet UIWindow *window;

@property (nonatomic, retain) RootViewController *rootViewController;

@end


//
//  FTPPhotosAppDelegate.m
//  FTPPhotos
//
//  Created by Aaron McLeod on 11-05-30.
//  Copyright 2011 __MyCompanyName__. All rights reserved.
//

#import "FTPPhotosAppDelegate.h"

@implementation FTPPhotosAppDelegate


@synthesize window=_window;

    @synthesize navigationController, rootViewController;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    navigationController = [[UINavigationController alloc] init];

    rootViewController = [[RootViewController alloc] init];
    [self.navigationController pushViewController:rootViewController animated:NO];
    [self.window addSubview:[self.navigationController view]];    
    [self.window makeKeyAndVisible];
    return YES;
}


@interface RootViewController : UITableViewController<UIImagePickerControllerDelegate> {
    NSMutableArray *photos;
    UIImagePickerController *picker;
    UIBarButtonItem *addPhotoButton;
}

@property (nonatomic, retain) NSMutableArray *photos;
@property (nonatomic, retain) UIImagePickerController *picker;
@property (nonatomic, retain) IBOutlet UIBarButtonItem *addPhotoButton;

- (void) loadPhotos;
- (IBAction) addPhoto;
- (UIImage*)imageWithImage:(UIImage*)image scaledToSize:(CGSize)newSize;
@end


#import "RootViewController.h"

@implementation RootViewController
@synthesize photos, picker, addPhotoButton;

- (void)viewDidLoad
{
    self.photos = [[NSMutableArray alloc] initWithCapacity:50];
    [self loadPhotos];
    [super viewDidLoad];
}

有什么想法吗？这是 XIB 的屏幕截图，

。

如果您需要更多信息，请告诉我。

Answer 1

使其成为 UINavigationController *navigationController，而不是根视图控制器。

然后在 applicationDidFinishLaunching 中，说

navigationController = [[UINavigationController alloc]init];
FirstViewController *firstView = [FirstViewController alloc]init];
[self pushViewController:firstView animated:NO];
firstView.title = @"TITLE";
[self addSubview:navigationController.view];

编辑：我的应用程序中的一些示例代码

AppDelegate.h

#import <UIKit/UIKit.h>

@interface DragonAge2AppDelegate : NSObject <UIApplicationDelegate> {
UIWindow *window;
UINavigationController *navigationController;
}

@property (nonatomic, retain) IBOutlet UIWindow *window;

@end

AppDelegate.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    
TitleClass *titlePage = [[TitleClass alloc]init];

navigationController = [[UINavigationController alloc]init];
titlePage.title = @"Dragon Age 2";
[navigationController pushViewController:titlePage animated:NO];
[titlePage release];

// Override point for customization after application launch.
[window addSubview:navigationController.view];
[self.window makeKeyAndVisible];

return YES;
}

Answer 2

您需要检查以下几点：

• 运行应用程序时是否执行了 application:didFinishLaunchingWithOptions: 中的代码？在此代码中添加 NSLog(@"app launch") 或在其中设置断点来检查它。如果未调用它，则您的 FTPPhotosAppDelegate 对象可能未设置为 XIB 中的 UIApplication 单例的委托（此连接应该完成默认情况下，如果您使用标准模板创建应用程序，但值得检查）
• AppDelegate 的 navigationController IBOutlet 是否正确连接到您实际的 UINavigationController在 XIB 中？检查（使用 NSLog 或断点）它不是 nil。
• 对于 XIB 中 UINavigationController 对象的视图 IBOutlet 也是如此：检查它是否正确连接，而不是 nil 。