Tiny OS X app based on http://cocoawithlove.com/2010/09/minimalist-cocoa-programming.html

main.m

#import <Cocoa/Cocoa.h>
#import <AppKit/AppKit.h>

#define NEW(a) [[a new] autorelease]

@interface Maign : NSObject
- (void)buttonAction:(id)sender;
@end

@implementation Maign
- (void)buttonAction:(id)sender
{
    id alert = [[[NSAlert alloc] init] autorelease];
    [alert setMessageText:@"I DIIIIID IT"];
    [alert addButtonWithTitle:@"OK"];
    [alert runModal];
}
@end

int main()
{
    [NSAutoreleasePool new];
    [NSApplication sharedApplication];
    [NSApp setActivationPolicy:NSApplicationActivationPolicyRegular];

    id menubar = [[NSMenu new] autorelease];
    id appMenuItem = [[NSMenuItem new] autorelease];
    [menubar addItem:appMenuItem];
    [NSApp setMainMenu:menubar];

    id appMenu = [[NSMenu new] autorelease];
    id appName = [[NSProcessInfo processInfo] processName];
    id quitTitle = [@"Quit " stringByAppendingString:appName];
    id quitMenuItem = [[[NSMenuItem alloc] initWithTitle:quitTitle
                                                  action:@selector(terminate:)
                                           keyEquivalent:@"q"] autorelease];
    [appMenu addItem:quitMenuItem];
    [appMenuItem setSubmenu:appMenu];

    id window = [[[NSWindow alloc] initWithContentRect:NSMakeRect(0, 0, 200, 200)
                                             styleMask:NSTitledWindowMask
                                               backing:NSBackingStoreBuffered
                                                 defer:NO] autorelease];
    [window cascadeTopLeftFromPoint:NSMakePoint(20, 20)];
    [window setTitle:appName];
    [window setBackgroundColor:[NSColor yellowColor]];

    id button = [[[NSButton alloc] initWithFrame:NSMakeRect(50, 50, 100, 30)] autorelease];
    [button setTitle:@":¬)"];
    [button setAction:@selector(buttonAction:)];
    [button setTarget:[[[Maign alloc] init] autorelease]];
    [[window contentView] addSubview:button];

    [window makeKeyAndOrderFront:nil];
    [NSApp activateIgnoringOtherApps:YES];
    [NSApp run];
    return 0;
}

Makefile

APP = Tiny App
APP_DIR = $(APP).app
BIN_DIR = $(APP_DIR)/Contents/MacOS
FRAMEWORKS = -framework Cocoa -framework AppKit

app:
	mkdir -p "$(BIN_DIR)"
	gcc $(FRAMEWORKS) -x objective-c -o "$(BIN_DIR)/$(APP)" main.m

clean:
	rm -rf "$(APP_DIR)"