有什么方法可以在C中使用Objective-C库? [英] is there any way to use Objective-C library in C?

问题描述

我想使用C中的以下代码(使用arm-gcc编译)

I want to use the below code from C (compile with arm-gcc)

NSString *newText;

CLLocationManager * locationManager = [[CLLocationManager alloc] init];
[locationManager startUpdatingLocation];
[locationManager setDesiredAccuracy:kCLLocationAccuracyNearestTenMeters];
//[locationManager setDelegate:self];

CLLocation* location = [locationManager location];

newText = [[NSString alloc] initWithFormat: @"Your Position : %f %f", [location horizontalAccuracy], [location verticalAccuracy]];

有什么方法可以在c中使用Objective-c库(例如在c中使用c ++库)?

Is there any way to use objective-c library in c (like using c++ library in c)?

推荐答案

基本上可以使用与在C语言中使用C ++库相同的方式.

It is possible basically in the same manner you would use C++ library in C.

您必须提供包装C API.如果定义普通C函数，则应该可以从另一个普通C可执行文件轻松访问它们.

You have to provide the wrapping C API. If you define plain C functions, they should be easily accessible from another plain C executable.

您将需要一些头文件:

#ifndef __OBJC__
typedef void* id;
#endif

id api_getlocation();
const char* api_location_to_text(id location);
void api_free_location(id location);

和代码(1):

id api_getlocation()
{
  CLLocationManager * locationManager = [[CLLocationManager alloc] init];  
  [locationManager startUpdatingLocation];
  [locationManager setDesiredAccuracy:kCLLocationAccuracyNearestTenMeters];
   //[locationManager setDelegate:self];

   CLLocation* location = [locationManager location];
   return [location retain];
}

const char* api_location_to_text(id location) 
{
   NSString* newText = [NSString stringWithFormat: @"Your Position : %f %f", [location horizontalAccuracy], [location verticalAccuracy]];

   return strdup([newText UTF8String]);
}

void api_free_location(id location)
{
    [location release];
}

然后您可以通过C代码使用它，包括头文件并调用这些C函数.

Then you could use it from C code, including your header file and calling these C function.

NB :如果您与Objective-C运行时库链接，则还应该能够通过调用objc_sendMsg直接向对象发送消息，但这在中会很麻烦. ...

NB: if you link with objective-c runtime library, you should be also able to directly send messages to the objects by calling objc_sendMsg, but this will prove to be a pain in ....

(1)我没有检查Objective-C代码是否真的有意义.

(1) I have not checked if the objective-c code actually makes sense.

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