Error compiling objective-c code

Question

Here it my code. It is very simple but I don't understand the error

#import <Foundation/Foundation.h>

@interface Car: NSObject

@property(nonatomic,retain) NSString *brand;
@property int year;

@end //Car Interface

#import "Car.h"

@implementation Car

@synthesize brand, year;

@end //Car Implementation

#import "Car.h"

int main (int argc, const char * argv[])
{
    int y;

    //Creo un nuovo oggetto
    Car *myCar = [[Car alloc] init];

    //Setto i parametri
    [myCar setBrand: @"BMW Z4"];

    NSLog (@"Inserisci data modello: ");
    scanf (" %i", &y); //E' buona norma lasciare uno spazio
    [myCar setYear: y];

    //Stampo a video i dati
    NSLog(@"Marca: %@ Anno: %i", [myCar brand], [myCar year]);

    return (0);
}

Here the errors I got:

car.m:5:1: error: ivar 'brand' used by '@synthesize' declaration must be an existing iva
car.m:5:1: error: ivar 'year' used by '@synthesize' declaration must be an existing ivar
car.m:7:1: warning: incomplete implementation of class 'Car' [enabled by default]
car.m:7:1: warning: method definition for '-setBrand:' not found [enabled by default]
car.m:7:1: warning: method definition for '-brand' not found [enabled by default]
car.m:7:1: warning: method definition for '-setYear:' not found [enabled by default]
car.m:7:1: warning: method definition for '-year' not found [enabled by default]

This is almost the same code as in your previous question http://stackoverflow.com/questions/17996426/any-mistakes-using-property-and-synthesize. Why do you accept the answer if it does not work for you? - And perhaps you should mention again that you are using **GNUstep**. — Martin R, Aug 01 '13 at 15:09
Yes it is the same code but I solved the previosly problem infact I have anymore that error. Now the problem is different. — Mazzy, Aug 01 '13 at 15:10
This is not about GNUstep. I'm using clang with GNUstep and I can compile your code just fine. — Fred Frith-MacDonald, Aug 02 '13 at 09:24

score 1 · Answer 1 · edited Jun 20 '20 at 09:12

1

This works fine when copied and pasted in to a new XCode Cocoa-based Command Line Tool project. The only difference is I added your code in to the @autoreleasepool:

Main.m

#import <Foundation/Foundation.h>
#import "Car.h"

int main(int argc, const char * argv[])
{

    @autoreleasepool {
        int y;
        
        //Creo un nuovo oggetto
        Car *myCar = [[Car alloc] init];
        
        //Setto i parametri
        [myCar setBrand: @"BMW Z4"];
        
        NSLog (@"Inserisci data modello: ");
        scanf (" %i", &y); //E' buona norma lasciare uno spazio
        [myCar setYear: y];
        
        //Stampo a video i dati
        NSLog(@"Marca: %@ Anno: %i", [myCar brand], [myCar year]);
    }
    return 0;
}

The answer by @Martin R. above indicates you're using GNUStep instead of XCode, so you may wish to add that tag, or seek advice specifically on GNUStep forums or chat rooms.

edited Jun 20 '20 at 09:12

Community

1
1

answered Aug 01 '13 at 15:26

Josh Whittington

705
3
10
23

According what you say, programming in XCode is totally difference from programming in GNUstep so this is the really reason – Mazzy Aug 01 '13 at 15:30
1

@Mazzy - Are you referring to the @autoreleasepool? That's just an automated memory management feature of Objective-C (as far as my limited knowledge extends) - but yes, XCode is its own IDE for sure. – Josh Whittington Aug 02 '13 at 04:20
1

This isn't about GNUstep, it's about the compiler. GCC is the problem, or may be a too old version of clang. Don't use GCC with Objective-C. If you know any newcomer, tell them they should (must) use clang, not gcc. Uninstall GCC if it doesn't hurt anyone. – Fred Frith-MacDonald Aug 02 '13 at 09:31

score 0 · Answer 2 · answered Jan 15 '14 at 01:57

    #import <Foundation/Foundation.h>

    @interface Car: NSObject
    {
    @protected 
            NSString *brand;
            int year;

    }

    @property(nonatomic,retain) NSString *brand;
    @property int year;

    @end //Car Interface

#import "Car.h";


    @implementation Car

    @synthesize brand, year;

    @end //Car Implementation


    int main (int argc, const char * argv[])
    {
        int y;

        //Creo un nuovo oggetto
        Car *myCar = [[Car alloc] init];

        //Setto i parametri
        [myCar setBrand: @"BMW Z4"];

        NSLog (@"Inserisci data modello: ");
        scanf (" %i", &y); //E' buona norma lasciare uno spazio
        [myCar setYear: y];

        //Stampo a video i dati
        NSLog(@"Marca: %@ Anno: %i", [myCar brand], [myCar year]);

        return (0);
    }

score -1 · Accepted Answer · answered Aug 01 '13 at 15:11

-1

you need to add the properties within the interface.

this

@interface Car {
    @protected
        NSString *brand;
        int year;
}


@property(nonatomic,retain) NSString *brand;
@property int year;

@end

instead of this

@interface Car: NSObject

@property(nonatomic,retain) NSString *brand;
@property int year;

@end //Car Interface

should work - but i haven't tried.

answered Aug 01 '13 at 15:11

jowe

32
1

Learn difference between ivars and properties first. – Kreiri Aug 01 '13 at 15:12
Yeah now it works...but thre reason it is not still clear. I will go to study – Mazzy Aug 01 '13 at 15:28

Error compiling objective-c code

3 Answers3

Main.m