如何纯粹用C编写iOS应用程序
我在这里读了学习C Objective-C之前？
通常我会用纯C代码代替一些Obj-C代码（毕竟你可以尽可能多地混合它们，Obj-C方法的内容可以完全是纯C代码）
这是真的？
是否有可能纯粹用C语言编写iPhone应用程序？
该死的，我花了一段时间，但我明白了：
main.c中：
#include <CoreFoundation/CoreFoundation.h> #include <objc/runtime.h> #include <objc/message.h> // This is a hack. Because we are writing in C, we cannot out and include // <UIKit/UIKit.h>, as that uses Objective-C constructs. // however, neither can we give the full function declaration, like this: // int UIApplicationMain (int argc, char *argv[], NSString *principalClassName, NSString *delegateClassName); // So, we rely on the fact that for both the i386 & ARM architectures, // the registers for parameters passed in remain the same whether or not // you are using VA_ARGS. This is actually the basis of the objective-c // runtime (objc_msgSend), so we are probably fine here, this would be // the last thing I would expect to break. extern int UIApplicationMain(int, ...); // Entry point of the application. If you don't know what this is by now, // then you probably shouldn't be reading the rest of this post. int main(int argc, char *argv[]) { // Create an @autoreleasepool, using the old-stye API. // Note that while NSAutoreleasePool IS deprecated, it still exists // in the APIs for a reason, and we leverage that here. In a perfect // world we wouldn't have to worry about this, but, remember, this is C. id autoreleasePool = objc_msgSend(objc_msgSend(objc_getClass("NSAutoreleasePool"), sel_registerName("alloc")), sel_registerName("init")); // Notice the use of CFSTR here. We cannot use an objective-c string // literal @"someStr", as that would be using objective-c, obviously. UIApplicationMain(argc, argv, nil, CFSTR("AppDelegate")); objc_msgSend(autoreleasePool, sel_registerName("drain")); } AppDelegate.c：
#import <objc/runtime.h> #import <objc/message.h> // This is equivalent to creating a @class with one public variable named 'window'. struct AppDel { Class isa; id window; }; // This is a strong reference to the class of the AppDelegate // (same as [AppDelegate class]) Class AppDelClass; // this is the entry point of the application, same as -application:didFinishLaunchingWithOptions: // note the fact that we use `void *` for the 'application' and 'options' fields, as we need no reference to them for this to work. A generic id would suffice here as well. BOOL AppDel_didFinishLaunching(struct AppDel *self, SEL _cmd, void *application, void *options) { // we +alloc and -initWithFrame: our window here, so that we can have it show on screen (eventually). // this entire method is the objc-runtime based version of the standard View-Based application's launch code, so nothing here really should surprise you. // one thing important to note, though is that we use `sel_getUid()` instead of @selector(). // this is because @selector is an objc language construct, and the application would not have been created in C if I used @selector. self->window = objc_msgSend(objc_getClass("UIWindow"), sel_getUid("alloc")); self->window = objc_msgSend(self->window, sel_getUid("initWithFrame:"), (struct CGRect) { 0, 0, 320, 480 }); // here, we are creating our view controller, and our view. note the use of objc_getClass, because we cannot reference UIViewController directly in C. id viewController = objc_msgSend(objc_msgSend(objc_getClass("UIViewController"), sel_getUid("alloc")), sel_getUid("init")); // creating our custom view class, there really isn't too much // to say here other than we are hard-coding the screen's bounds, // because returning a struct from a `objc_msgSend()` (via // [[UIScreen mainScreen] bounds]) requires a different function call // and is finicky at best. 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 view controller, and add the viewController to the window. objc_msgSend(objc_msgSend(viewController, sel_getUid("view")), sel_getUid("addSubview:"), view); objc_msgSend(self->window, sel_getUid("setRootViewController:"), viewController); // finally, we display the window on-screen. objc_msgSend(self->window, sel_getUid("makeKeyAndVisible")); return YES; } // note the use of the gcc attribute extension (constructor). // Basically, this lets us run arbitrary code before program startup, // for more information read here: http://stackoverflow.com/questions/2053029 __attribute__((constructor)) static void initAppDel() { // This is objc-runtime gibberish at best. We are creating a class with the // name "AppDelegate" that is a subclass of "UIResponder". Note we do not need // to register for the UIApplicationDelegate protocol, that really is simply for // Xcode's autocomplete, we just need to implement the method and we are golden. AppDelClass = objc_allocateClassPair(objc_getClass("UIResponder"), "AppDelegate", 0); // Here, we tell the objc runtime that we have a variable named "window" of type 'id' class_addIvar(AppDelClass, "window", sizeof(id), 0, "@"); // We tell the objc-runtime that we have an implementation for the method // -application:didFinishLaunchingWithOptions:, and link that to our custom // function defined above. Notice the final parameter. This tells the runtime // the types of arguments received by the function. class_addMethod(AppDelClass, sel_getUid("application:didFinishLaunchingWithOptions:"), (IMP) AppDel_didFinishLaunching, "i@:@@"); // Finally we tell the runtime that we have finished describing the class and // we can let the rest of the application use it. objc_registerClassPair(AppDelClass); }
View.c
#include <objc/runtime.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, struct CGRect rect) { // We are simply getting the graphics context of the current view, // so we can draw to it CGContextRef context = UIGraphicsGetCurrentContext(); // Then we set it's fill color to white so that we clear the background. // Note the cast to (CGFloat []). Otherwise, this would give a warning // saying "invalid cast from type 'int' to 'CGFloat *', or // 'extra elements in initializer'. Also note the assumption of RGBA. // If this wasn't a demo application, I would strongly recommend against this, // but for the most part you can be pretty sure that this is a safe move // in an iOS application. CGContextSetFillColor(context, (CGFloat []){ 1, 1, 1, 1 }); // here, we simply add and draw the rect to the screen CGContextAddRect(context, (struct CGRect) { 0, 0, 320, 480 }); CGContextFillPath(context); // and we now set the drawing color to red, then add another rectangle // and draw to the screen CGContextSetFillColor(context, (CGFloat []) { 1, 0, 0, 1 }); CGContextAddRect(context, (struct CGRect) { 10, 10, 20, 20 }); CGContextFillPath(context); } // 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(objc_getClass("UIView"), "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); }
这是丑陋的，但它的作品。
如果你想下载这个， 你可以从我的Dropbox 在这里
你可以从我的GitHub仓库中获取：
Objective-C是C语言的超集，所以理论上可以用C编写一个程序，但是，除非你熟练掌握OpenGL ES ，否则你至less需要做一些 objC（ Even Rich的示例有一个const NSString * ），否则你必须自己写视图。
好的，以上是完全错误的。 让我说，我很惊讶，Rich实现了这个崇高的目标，所以我把它移植到了mac（源码在这里 ）。 下面的文件没有标题，不链接到cocoa，也没有一个nib的项目：
AppDelegate.m
#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; }
View.m
#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); }
prefix.pch
// // 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
我在这里读了Objective-C之前的学习C？
通常我会用纯C代码代替一些Obj-C代码（毕竟你可以尽可能多地混合它们，Obj-C方法的内容可以完全是纯C代码）
这是真的？
我可以纯粹用C编程语言构build一个iPhone应用程序吗？
引用的段落是真实的，但是你的问题的答案是否定的。
为了说明Mecki在其他问题上回答什么：
- (void) drawRect:(CGRect)dirtyRect { //Objective-C CGContextRef context = UIGraphicsGetCurrentContext(); //C CGContextSetRGBFillColor(context, 1.0, 0.0, 0.0, 1.0); //C CGContextFillRect(context, dirtyRect); //C } //Objective-C (balances above “- (void) drawRect:…” line)
在这个方法中除了纯粹的C代码外没有什么东西，但是方法本身就是Objective-C代码，就像包含这个方法的类一样。
所以有可能做Mecki所说的，但是你不能（实际上，就像Richard J. Ross III所表明的那样，这在技术上是可能的，但是相当多的打字）在纯C中写了一个完整的Cocoa Touch程序。
实际上，这里发表的一些代码，用C编写，仍然是调用objective-C代码:)。 当他问的时候，我不知道这是否符合原始海报的情况
是否有可能纯粹用C语言编写iPhone应用程序？
但我会同意这样的观点，一般来说，对于使用GUI的应用程序，您需要在OpenGL（C语言）中编写GUI。
我认为这是大多数游戏所做的，对吧？ 尽pipe我不确定在C中是否可以访问iPhone的I / O（例如触摸屏）
最后但并非最不重要的是，把代码写在岩石上的人！ 🙂
