Compiling Objective-C project on Linux (Ubuntu)
- by Alex
How to make an Objective-C project work on Ubuntu?
My files are:
Fraction.h
#import <Foundation/NSObject.h>
@interface Fraction: NSObject {
int numerator;
int denominator;
}
-(void) print;
-(void) setNumerator: (int) n;
-(void) setDenominator: (int) d;
-(int) numerator;
-(int) denominator;
@end
Fraction.m
#import "Fraction.h"
#import <stdio.h>
@implementation Fraction
-(void) print {
printf( "%i/%i", numerator, denominator );
}
-(void) setNumerator: (int) n {
numerator = n;
}
-(void) setDenominator: (int) d {
denominator = d;
}
-(int) denominator {
return denominator;
}
-(int) numerator {
return numerator;
}
@end
main.m
#import <stdio.h>
#import "Fraction.h"
int main( int argc, const char *argv[] ) {
// create a new instance
Fraction *frac = [[Fraction alloc] init];
// set the values
[frac setNumerator: 1];
[frac setDenominator: 3];
// print it
printf( "The fraction is: " );
[frac print];
printf( "\n" );
// free memory
[frac release];
return 0;
}
I've tried two approaches to compile it:
Pure gcc:
$ sudo apt-get install gobjc gnustep gnustep-devel
$ gcc `gnustep-config --objc-flags` -o main main.m -lobjc -lgnustep-base
/tmp/ccIQKhfH.o:(.data.rel+0x0): undefined reference to `__objc_class_name_Fraction'
I created a GNUmakefile Makefile:
include ${GNUSTEP_MAKEFILES}/common.make
TOOL_NAME = main
main_OBJC_FILES = main.m
include ${GNUSTEP_MAKEFILES}/tool.make
... and ran:
$ source /usr/share/GNUstep/Makefiles/GNUstep.sh
$ make
Making all for tool main...
Linking tool main ...
./obj/main.o:(.data.rel+0x0): undefined reference to `__objc_class_name_Fraction'
So in both cases compiler gets stuck at
undefined reference to `__objc_class_name_Fraction'
Do you have and idea how to resolve this issue?
