Question

I am including a file like this:

#import "BannerPhoneContentController.h"

however, when I try to use it like this:

bannerContentController = [[BannerPhoneContentController alloc] init];

I get the error:

Use of undeclared identifier 'BannerPhoneContentController';

what could be causing the code to seemingly ignore my import?

this is the header for banner content controller.

#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>

#import "BannerContentController.h"

@interface BannerPhoneContentController : BannerContentController <UIScrollViewDelegate>
{   
    UIScrollView *scrollView;
    UIPageControl *pageControl;
    NSMutableArray *viewControllers;

    // To be used when scrolls originate from the UIPageControl
    BOOL pageControlUsed;
}

@property (nonatomic, retain) UIScrollView *scrollView;
@property (nonatomic, retain) UIPageControl *pageControl;

@property (nonatomic, retain) NSMutableArray *viewControllers;

- (IBAction)changePage:(id)sender;

@end

EDIT bannerContentController is of type BannerContentController NOT BannerPhoneContentController. The latter is a subtype of the former. It is definitely worth noting that this exact code works just fine in another app, so it’s nothing to do with the code itself – just how it’s being included apparently. I’m stumped.

EDIT ok found the problem – not sure how to fix it. I generated the preprocessed file and the header file it’s included is in fact this:

#import <UIKit/UIKit.h>
#import <Foundation/Foundation.h>

#import "ContentController.h"

@interface PhoneContentController : ContentController <UIScrollViewDelegate>
{   
    UIScrollView *scrollView;
    UIPageControl *pageControl;
    NSMutableArray *viewControllers;

    // To be used when scrolls originate from the UIPageControl
    BOOL pageControlUsed;
}

@property (nonatomic, retain) UIScrollView *scrollView;
@property (nonatomic, retain) UIPageControl *pageControl;

@property (nonatomic, retain) NSMutableArray *viewControllers;

- (IBAction)changePage:(id)sender;

@end

note the difference – all the ‘Banner’s are missing. This is what the file used to look like. However, I’ve checked and the file that’s in the project is the one I posted at the top. I tried cleaning the solution and building again. How can I fix this and why has it happened?

EDIT The file that I’m including all this in is part of a code library. I have now created a new project, imported the code library and included all of this in that library once again in exactly the same way. and it works. I have looked over the two projects and the code in question is identical. This must be a project setting?

Answer 1

It looks for me like recursive import. Say, BannerContentController.h imports BannerPhoneContentController.h, and BannerPhoneContentController.h imports BannerContentController.h.

If it is the case, then you should resolve recursive dependencies. E.g. using forward declaration.