iOS application in C

AppDelegate.c

#import "AppDelegate.h"

#import <CoreGraphics/CoreGraphics.h>

#import "objc-insanity.h"

void initializeAppDelegate()
{
    Class c = objc_allocateClassPair(objc_getClass("NSObject"), "AppDelegate", 0);

    class_addProtocol(c, objc_getProtocol("UIApplicationDelegate"));
    class_addMethod(c, S("application:didFinishLaunchingWithOptions:"), (IMP)didFinishLaunching, "B@:@@");
    objc_registerClassPair(c);
}

BOOL didFinishLaunching(id self, SEL sel, id application, id launchOptions)
{
    id screen     = objc_method(id, TYPE(Class, SEL), objc_getClass("UIScreen"), S("mainScreen"));
    CGRect bounds = objc_method(CGRect, TYPE(id, SEL), screen, S("bounds"));

    id window = class_createInstance(objc_getClass("UIWindow"), 0);
    window = objc_method(id, TYPE(id, SEL, CGRect), window, S("initWithFrame:"), bounds);

    id viewController = class_createInstance(objc_getClass("UIViewController"), 0);
    viewController = objc_method(id, TYPE(id, SEL), viewController, S("init"));

    id color = objc_method(id, TYPE(Class, SEL), objc_getClass("UIColor"), S("yellowColor"));
    id view = objc_method(id, TYPE(id, SEL), viewController, S("view"));
    objc_method(void, TYPE(id, SEL, id), view, S("setBackgroundColor:"), color);

    objc_method(void, TYPE(id, SEL, id), window, S("setRootViewController:"), viewController);

    objc_method(void, TYPE(id, SEL), window, S("makeKeyAndVisible"));
    return YES;
}

AppDelegate.h

#import <objc/objc.h>

void initializeAppDelegate();
BOOL didFinishLaunching(id self, SEL sel, id application, id launchOptions);

main.c

#import <CoreFoundation/CoreFoundation.h>
#import "AppDelegate.h"
#import "objc-insanity.h"

void *objc_autoreleasePoolPush(void);
void objc_autoreleasePoolPop(void *pool);
int UIApplicationMain(int argc, char** argv, id principalClassName, id delegateClassName);

int main(int argc, char** argv) {
    void* pool = objc_autoreleasePoolPush();
    initializeAppDelegate();
    int retval = UIApplicationMain(argc, argv, nil, (id)CFSTR("AppDelegate"));
    objc_autoreleasePoolPop(pool);
    return retval;
}

objc-insanity.h

#import <objc/message.h>

#define TYPE(...) __VA_ARGS__
#define S(n) sel_getUid(n)
#define objc_method(return_type, type, ...) ((return_type(*)(type))objc_msgSend)(__VA_ARGS__)