iphone - AppDelegate 导航错误

Question

- (void)applicationDidFinishLaunching:(UIApplication *)application {   
    NSError *error = nil;
    NSString *username = [[NSUserDefaults standardUserDefaults] objectForKey:@"username"];
    NSString *str =  [SFHFKeychainUtils getPasswordForUsername:username andServiceName:@"mybibleapp" error:&error];
    NSLog(@"previous un");
    NSLog(@"%@", str);
    if(str != nil)
    {
      main_page *detailViewController = [[main_page alloc] initWithNibName:@"main_page" bundle:nil];
      // Pass the selected object to the new view controller.
      // detailViewController.localStringtextnote = localStringtextnote;
      [self.navigationController pushViewController:detailViewController animated:YES];
      [detailViewController release];
    }

当我将这段代码用于导航到 main_page 时，它​​显示一个错误，即 property navigationController not found on object of appdelegate 所以我将这段代码放在上面

 main_page  *log = [[main_page alloc] initWithNibName:@"main_page" bundle:nil];
 [window addSubview:tabController.view];
 [window addSubview:log.view];
 [window makeKeyAndVisible];

页面被重定向到 main_page 但没有任何东西以这种方式工作。 main_page 中没有导航工作，我无法从 main_page 重定向任何页面。那么我该怎么做才能解决这些错误。

Answer 1

您可以创建一个不带 nib 的“代理”viewController，它被加载到 MainWindow 的 navigationController 中，然后在代理的 viewDidLoad 中执行如下操作

NSError *error = nil;
NSString *username = [[NSUserDefaults standardUserDefaults] objectForKey:@"username"];
NSString *str =  [SFHFKeychainUtils getPasswordForUsername:username andServiceName:@"mybibleapp" error:&error];
NSLog(@"previous un");

NSLog(@"%@", str);

UIViewController *controller;

if (!error && nil != str) {
    controller = [[DetailViewController alloc] init];
} else {
    controller = [[LoginViewController alloc] init];
}
[[self navigationController] pushViewController:controller animated:YES];
[controller release];