Question

I have an Objective-C view controller class, from which I am trying to call a straight-C (not Objective-C) function. I want to pass in a string variable by reference, set its value inside the C function, and then back in my view controller I want to convert this to a normal NSString object.

Since I can’t pass in an NSString object directly, I need to create and pass in either a char pointer or a char array, and then convert it to an NSString object after the function returns.

Can anyone point me to a simple code example that shows how to do this? I’m not strong in either Objective-C or regular C, so manipulating strings is extremely difficult for me.

Answer 1

Maybe something like this

bool doSomethingToMyString(const char* originalString, char *buffer, unsigned int size)
{
    bool result = 0;
    if (size >= size_needed)
    {
        sprintf(buffer, "The new content for the string, maybe dependent on the originalString.");
        result = 1;
    }
    return result;
}

...
- (void) objectiveCFunctionOrSomething:(NSString *)originalString
{
    char myString[SIZE];
    if (doSomethingToMyString([originalString UTF8String], myString, SIZE))
    {
        NSString *myNSString = [NSString stringWithCString:myString encoding:NSUTF8StringEncoding];
        // alright!
    }
}

or, you know, something to that effect.