Question

I’m new in objective-c and makefiles, currently I’m trying to get an objective-c and Gtk+ “hello world” to compile via make.
The make code is as follows

# Suffixes

.SUFFIXES: .o .m
.m.o:
    $(CC) -c $(CFLAGS) $<

# Macros 
CC = gcc
CFLAGS = -g
GTKFLAGS= `pkg-config --cflags --libs gtk+-2.0`
LIBS = -lobjc
SRC = main.m  MainWindow.m
OBJ = main.o MainWindow.o
PROG = gnulog514

# Explicit rule
all: hist

hist: $(OBJ)
    $(CC) $(CFLAGS) -o main $(OBJ) $(GTKFLAGS) $(LIBS)

# Implicit rules
MainWindow.o: MainWindow.h MainWindow.m 

and I get the following output after make.

gcc -c -g main.m
In file included from main.m:1:0:
MainWindow.h:1:20: fatal error: gtk/gtk.h: No such file or directory
compilation terminated.
make: *** [main.o] Error 1

Anything else you may need just ask.

UPDATE:

I’ve got something else that may help,
when issuing the command

$ gcc `pkg-config --cflags --libs gtk+2.0` -lgnustep-base -fconstant-string-class=NSConstantString -o "./myprogram" $(find . -name '*.m') -I /usr/include/GNUstep/ -L /usr/lib/GNUstep/ -std=c99 -O3

(Got the error gtk+2.0 to gtk+-2.0)I get the following output

Package gtk+2.0 was not found in the pkg-config search path.
Perhaps you should add the directory containing `gtk+2.0.pc'
to the PKG_CONFIG_PATH environment variable
No package 'gtk+2.0' found
In file included from ./main.m:1:0:
./MainWindow.h:1:20: fatal error: gtk/gtk.h: No such file or directory
compilation terminated.
In file included from ./MainWindow.m:1:0:
./MainWindow.h:1:20: fatal error: gtk/gtk.h: No such file or directory
compilation terminated.

I’ll get that fixed and come back here to keeping updated this question until solution.

Answer 1

I got it to work. Long story short instead of using Foundations headers I use objc headers.

My Makefile looks like that

# Suffixes
%.o : %.m
    $(CC) $(CCFLAGS) $(CCGTK) -c -o $@ $^

# Macros
CC = gcc
CCFLAGS = -lobjc
CCGTK = `pkg-config --cflags --libs gtk+-2.0` 
SOURCES= $(wildcard *.m) 
OBJECTS= $(SOURCES:.m=.o)
PROG = glog514

# Targets
all: $(SOURCES) $(PROG)

$(PROG): $(OBJECTS)
    $(CC) -o $@ $(OBJECTS) $(CCFLAGS) $(CCGTK) 

clean:
    rm -f $(OBJECTS) $(PROG)

And if you want to try by yourself my main.m

#import "MainWindow.h"

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

  //init gtk engine
  gtk_init(&argc, &argv);

  //set up GUI
  MainWindow *mainWindow = [[MainWindow alloc] initWithArgCount:&argc ArgVals:argv];

  //begin the GTK loop
  [mainWindow startGtkMainLoop];

  //free the GUI
  [mainWindow free];

  //exit application
  return 0;
}

my MainWindow.h

#include <objc/Object.h>
#include <gtk/gtk.h>

id myMainWindow;

@interface MainWindow:Object
{
  // Main GTKWindow
  GtkWidget *mainWindow;
  GtkWidget *button;
}

-(id)initWithArgCount:(int *)argc ArgVals:(char *[])argv;

-(void)destroyWidget;

-(void)startGtkMainLoop;

-(void)printSomething;

void on_MainWindow_destroy(GtkObject *object, gpointer user_data);

void on_btnPushMe_clicked(GtkObject *object, gpointer user_data);

@end

my MainWindow.m

#include "MainWindow.h"
#include <gtk/gtk.h>

@implementation MainWindow


-(id)initWithArgCount:(int *)argc ArgVals:(char *[])argv {
  //call parent class’ init
  if (self = [super init]) {
    //setup the window
    mainWindow = gtk_window_new (GTK_WINDOW_TOPLEVEL);

    gtk_window_set_title (GTK_WINDOW (mainWindow), "Hello World");
    gtk_window_set_default_size(GTK_WINDOW(mainWindow), 230, 150);

    //setup the button
    button = gtk_button_new_with_label ("Push me!");

    gtk_container_add (GTK_CONTAINER (mainWindow), button);

    //connect the signals
    g_signal_connect (mainWindow, "destroy", G_CALLBACK (on_MainWindow_destroy), NULL);
    g_signal_connect (button, "clicked", G_CALLBACK (on_btnPushMe_clicked), NULL);

    //force show all
    gtk_widget_show_all(mainWindow);
  }

  //assign C-compatible pointer
  myMainWindow = self;

  //return pointer to this object
  return self;
}

-(void)startGtkMainLoop {
  //start gtk loop
  gtk_main();
}

-(void)printSomething{

}

-(void)destroyWidget{
  myMainWindow = NULL;

  if(GTK_IS_WIDGET (button)){
    //clean up the button
    gtk_widget_destroy(button);
  }

  if(GTK_IS_WIDGET (mainWindow)){
    //clean up the main window
    gtk_widget_destroy(mainWindow);
  }
}

-(void)dealloc{
  [self destroyWidget];

  [super dealloc];
}

void on_MainWindow_destroy(GtkObject *object, gpointer user_data){
  //exit the main loop
  gtk_main_quit();
}

void on_btnPushMe_clicked(GtkObject *object, gpointer user_data){
  printf("Button was clicked\n");

  //call Objective-C function from C function using global object pointer
  [myMainWindow printSomething];
}

@end

Just put all the files in the same folder and run make, you’ll get a compiled file called glog514, then execute it and you’ll get the nice gtk window.

./glog514

cheers,