Install Objective-C on Linux (GNUstep)

Install the packages

sudo apt-get install gobjc gnustep gnustep-devel -y

• gobjc is the Objective-C front end of GCC.
• gnustep and gnustep-devel give you the Foundation library and tools.

Create a test program

Create a file hello.m:

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    NSLog (@"hello world");
    [pool drain];
    return 0;
}

Load the GNUstep settings

. /usr/share/GNUstep/Makefiles/GNUstep.sh

Compile

gcc hello.m -o hello `gnustep-config --objc-flags` -lgnustep-base -lobjc

The part in backticks adds the compiler flags of GNUstep. -lgnustep-base and -lobjc link the libraries.

Run

./hello

You see a line with a time stamp and "hello world".

Features of Objective-C

1. Object-oriented programming on top of C.
2. Dynamic typing and binding.
3. Compatible with C. You can mix C code in.
4. A messaging system. Objects talk by sending messages.
5. Automatic reference counting (ARC) in modern compilers.
6. Frameworks. Foundation and others.
7. A dynamic runtime.
8. Protocols (like interfaces).

Quick recap

• sudo apt-get install gobjc gnustep gnustep-devel.
• Source GNUstep.sh and compile with the gnustep-config flags.
• Run ./hello.