Why can't I push a new view controller onto the current view?

Question

I am using the following code and getting the following errors:

Answer 1

change [NSBundle mainBundle] to nil make sure you have import ChangePasscode.h on top of the M file

Answer 2

I am thinking this is a classic case of circular references. Maybe the two classes reference each other? Because of this forward declaration you might get all kinds of warnings when trying to reference the class name or properties of the class that has the forward declaration.

Where all have you included ChangePasscode. Also use #import rather than #include.

UPDATE: To solve your ld: duplicate symbol... error

It seems that you are compiling the same class ChangePasscode two times in different places of your code. This may happen in the following cases.

1. You have put the same class implementation into two different files
2. You actually have just one implementation of this class, however you are also linking in your project a framework or library containing a class whose name is exactly the same of yours.
3. You could also get this error if you mistakenly let XCode's auto-complete for #import statements specify the '.m" file for the 'duplicate' class instead of the '.h'.

Try finding in the whole project your class and make sure only one copy is available within your project.

Answer 3

I'm going to say that you've not imported ChangePasscode.h in your current file.

Update: In response to comment thread below, you'll need to actually create a nav structure if you want to push view controllers. The preferred way in iOS 5 is as follows:

// AppDelegate.h
// …Other existing code
@property (nonatomic, retain) UINavigationController *navController;
@end

// AppDelegate.m
@synthesize navController;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  navController = [[UINavigationController alloc] initWithRootViewController:viewController];
  self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
  self.window.rootViewController = navController;
  self.window.backgroundColor = [UIColor whiteColor];
  [self.window makeKeyAndVisible];
  return YES;
}

Answer 4

use

@class ChangePasscode;

rather than using

#import ChangePasscode.h