Question

I have two classes.

APPagine.h

#import <Foundation/Foundation.h>
@interface APPagineMedia : NSObject
@property (nonatomic, retain) NSString *Immagine;
@property (nonatomic, retain) NSString *Video;
@end

@interface APPagineDescription : NSObject
@property (nonatomic, retain) NSString *Descrizione;
@end

@interface APPagineSommarioLinee : NSObject
@property (nonatomic, retain) NSString *Description;
@property (nonatomic, assign) int IdLinea;
@end

@interface APPagineSommarioCategorie : NSObject
@property (nonatomic, retain) NSString *Nome;
@property (nonatomic, assign) int DestId;
@property (nonatomic, retain) APPagineSommarioLinee *Linee;
@end

@interface APPagineSommario : NSObject
@property (nonatomic, retain) APPagineSommarioCategorie *Categorie;
@end

@interface APPagine : NSObject
@property (nonatomic, assign) NSString *Layout;
@property (nonatomic, assign) int Indice;
@property (nonatomic, retain) NSString *Titolo;
@property (nonatomic, retain) APPagineMedia *Media;
@property (nonatomic, retain) APPagineDescription *Descrizione;
@property (nonatomic, retain) APPagineSommario *Sommario;
@end

APXmlData.h

@interface APXmlData : NSObject

@property (nonatomic, retain) NSString *Lingua;
@property (nonatomic, assign) float Versione;
@property (nonatomic, assign) long long Timestamp;
@property (nonatomic, retain) APPagine    *Pagine;
@property (nonatomic, retain) APCategorie *Categorie;
@property (nonatomic, retain) APCarousel  *Carousel;

@end

---

and finally in my controller interface:

#import "APXmlData.h"
@interface APViewController : UIViewController
{
  APXmlData *_XmlData;
}
@end

and in implementation:

_XmlData.Timestamp = 123;
_XmlData.Version = 1.0;
_XmlData.Pagine = [[APPagine alloc] init];
_XmlData.Pagine.Layout = @"a";
_XmlData.Pagine.Indice = 1;
_XmlData.Pagine.Titolo = @"titolo";
//[...]

---

But,
in when i go to set data to

_XmlData.Pagine = [[APPagine alloc] init];

he returns me a linker error, the classic

Undefined symbols for architecture i386:
“_OBJC_CLASS_$_APPagineDescription”, referenced from:
objc-class-ref in APPagine.o

“_OBJC_CLASS_$_APPagineMedia”, referenced from:
objc-class-ref in APViewController.o
objc-class-ref in APPagine.o

“_OBJC_CLASS_$_APPagineSommario”, referenced from:
objc-class-ref in APPagine.o

ld: symbol(s) not found for architecture i386 clang: error: linker command failed with exit code 1
(use -v to see invocation)

My question is: what is correct way to import the classes in my controller?
Should be use #import or @class?
In that order?
What are the classes that require @class or #import?

NOTE

In Build -> Compile Sources, both files are properly configured.
If i remove _XmlData.Pagine = [[APPagine alloc] init]; the apps run well

thanks.

Answer 1

The error you receive is a linker error, not a compiler error, so it looks like your #import was done correctly. Linker errors occur when the program linker cannot find the implementation. I would suggest that you check:

• That you have the corresponding @implementation in e.g. APPagine.m
• That APPagine.m is included in the project and active for your target in XCode