Objective c wrapper for a c file - objective-c

Question

I went through quite a number of websites, but everywhere they have given how to write a wrapper for a c++ library.
Now, I have a .c file which i want to integrate to my application. Since Objective c is an objected oriented extension of c, will i actually have to write wrapper for it? if yes, how to do it? if i dont have to, then how to use the c code in my project?
EDIT : ok.. what i have to do is add the file into my project and use the functions? how exactly to do it?? just like normal c call? what if i have to pass parameters?
Let say i have a function which returns a string, first of all how do i call that function? and if it returns a string, can i store that value in a normal NSString?? or should i declare a c string for it??
Thanks in advance

Answer 1

You can simply use your C code as usual:
-(void)writeString:(NSString*)data toFile:(NSString*)filename {
FILE* output = fopen([filename UTF8String], "w");
fprintf(output, "%s", [data UTF8String]);
fclose(output);
}
For other .c files, simply #include the corresponding header. Then, you can just call its functions.
For example, if this was foo.h:
int add(int a, int b);
And foo.c:
#include "foo.h"
int add(int a, int b) {
return a + b;
}
Then in your Objective-C code (Bar.m):
-(int)addA:(int)a andB:(int)b {
return add(a, b);
}
That is basically a wrapper right there. However, wrappers are not needed for C code in Objective-C. Even C++ functions do not need wrappers, as there are .mm files which are Objective-C++ sources.
Edit:
To call C functions with parameters, just call them with parameters. Literally ANY valid C program is also a valid Objective-C program. If it can compile as a .c file, it'll compile as a .m file.
To convert a C string (char*) to an NSString:
const char* myString = "Hello!";
NSString* myNSString = [NSString stringWithUTF8String:myString];