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copied!<p>Objective-C is a superset of the C-language, so it is theoretically possible to write a program entirely in C, however, unless you are thoroughly versed in <code>OpenGL ES</code>, You'll need to do at least <strong><em>some</em></strong> objC (<strike>Even Rich's sample has a const NSString* in it</strike>), else you'll have to write the views yourself.</p> <p>OK, the above is completely wrong. Let me say, I'm astounded Rich achieved this lofty goal, so I ported it over to the mac (source <a href="https://github.com/CodaFi/C-Macs" rel="noreferrer">here</a>). The files below have no headers, do not link to Cocoa, nor does the project have a nib:</p> <p><strong>AppDelegate.m</strong></p> <pre><code>#include <objc/runtime.h> #include <objc/message.h> extern id NSApp; struct AppDel { Class isa; //Will be an NSWindow later, for now, it's id, because we cannot use pointers to ObjC classes id window; }; // This is a strong reference to the class of the AppDelegate // (same as [AppDelegate class]) Class AppDelClass; BOOL AppDel_didFinishLaunching(struct AppDel *self, SEL _cmd, id notification) { //alloc NSWindow self->window = objc_msgSend(objc_getClass("NSWindow"), sel_getUid("alloc")); //init NSWindow //Adjust frame. Window would be about 50*50 px without this //specify window type. We want a resizeable window that we can close. //use retained backing because this thing is small anyhow //return no because this is the main window, and should be shown immediately self->window = objc_msgSend(self->window, sel_getUid("initWithContentRect:styleMask:backing:defer:"),(NSRect){0,0,1024,460}, (NSTitledWindowMask|NSClosableWindowMask|NSResizableWindowMask|NSMiniaturizableWindowMask),NSBackingStoreRetained,NO); //send alloc and init to our view class. Love the nested objc_msgSends! id view = objc_msgSend(objc_msgSend(objc_getClass("View"), sel_getUid("alloc")), sel_getUid("initWithFrame:"), (struct CGRect) { 0, 0, 320, 480 }); // here we simply add the view to the window. objc_msgSend(self->window, sel_getUid("setContentView:"), view); objc_msgSend(self->window, sel_getUid("becomeFirstResponder")); //makeKeyOrderFront: NSWindow to show in bottom left corner of the screen objc_msgSend(self->window, sel_getUid("makeKeyAndOrderFront:"), self); return YES; } static void initAppDel() { //Our appDelegate should be NSObject, but if you want to go the hard route, make this a class pair of NSApplication and try initing those awful delegate methods! AppDelClass = objc_allocateClassPair((Class) objc_getClass("NSObject"), "AppDelegate", 0); //Change the implementation of applicationDidFinishLaunching: so we don't have to use ObjC when this is called by the system. class_addMethod(AppDelClass, sel_getUid("applicationDidFinishLaunching:"), (IMP) AppDel_didFinishLaunching, "i@:@"); objc_registerClassPair(AppDelClass); } void init_app(void) { objc_msgSend( objc_getClass("NSApplication"), sel_getUid("sharedApplication")); if (NSApp == NULL) { fprintf(stderr,"Failed to initialized NSApplication... terminating...\n"); return; } id appDelObj = objc_msgSend( objc_getClass("AppDelegate"), sel_getUid("alloc")); appDelObj = objc_msgSend(appDelObj, sel_getUid("init")); objc_msgSend(NSApp, sel_getUid("setDelegate:"), appDelObj); objc_msgSend(NSApp, sel_getUid("run")); } //there doesn't need to be a main.m because of this little beauty here. int main(int argc, char** argv) { //Initialize a valid app delegate object just like [NSApplication sharedApplication]; initAppDel(); //Initialize the run loop, just like [NSApp run]; this function NEVER returns until the app closes successfully. init_app(); //We should close acceptably. return EXIT_SUCCESS; } </code></pre> <p><strong>View.m</strong></p> <pre><code>#include <objc/runtime.h> #include <objc/message.h> #include <ApplicationServices/ApplicationServices.h> // This is a strong reference to the class of our custom view, // In case we need it in the future. Class ViewClass; // This is a simple -drawRect implementation for our class. We could have // used a UILabel or something of that sort instead, but I felt that this // stuck with the C-based mentality of the application. void View_drawRect(id self, SEL _cmd, CGRect rect) { //make a red NSColor object with its convenience method id red = objc_msgSend(objc_getClass("NSColor"), sel_getUid("redColor")); // fill target rect with red, because this is it! NSRect rect1 = NSMakeRect ( 21,21,210,210 ); objc_msgSend(red, sel_getUid("set")); NSRectFill ( rect1 ); } // Once again we use the (constructor) attribute. generally speaking, // having many of these is a very bad idea, but in a small application // like this, it really shouldn't be that big of an issue. __attribute__((constructor)) static void initView() { // Once again, just like the app delegate, we tell the runtime to // create a new class, this time a subclass of 'UIView' and named 'View'. ViewClass = objc_allocateClassPair((Class) objc_getClass("NSView"), "View", 0); // and again, we tell the runtime to add a function called -drawRect: // to our custom view. Note that there is an error in the type-specification // of this method, as I do not know the @encode sequence of 'CGRect' off // of the top of my head. As a result, there is a chance that the rect // parameter of the method may not get passed properly. class_addMethod(ViewClass, sel_getUid("drawRect:"), (IMP) View_drawRect, "v@:"); // And again, we tell the runtime that this class is now valid to be used. // At this point, the application should run and display the screenshot shown below. objc_registerClassPair(ViewClass); } </code></pre> <p><strong>prefix.pch</strong></p> <pre><code>// // Prefix header for all source files of the 'CBasedMacApp' target in the 'CBasedMacApp' project // #ifdef __OBJC__ #import <Foundation/Foundation.h> #import <AppKit/AppKit.h> #endif </code></pre> <p><img src="https://i.stack.imgur.com/umwxu.png" alt="enter image description here"></p>

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