Question

I’ve been learning Obj-C since getting a MBP about a month ago. I’m fairly comfortable with what I’m learning & things are slotting in to my rusty old brain pretty well. Except there’s one thing I’m just not sure if I’m overlooking, or if just going over my head, or I’m looking for something that isn’t there.

Most languages I’ve used have a way of slotting in an inline function call to simplify the coding, & I’m just not sure how this translates in Obj-C. Especially I’m referring to when the function being called is in a separate file, for the coding purposes of keeping similar functions together.

So far, the only way I’ve seen in Obj-C guides & tutorials is to create a class with methods & then instantiate that class (within the class you’re working) to access the method in a [message]. Is this the way it’s done in Obj-C? The only way? The best way for some reason? I know classes have their place in many languages & I use them myself, but I’m referring to simple little inline function calls where I usually wouldn’t go to the trouble of creating a complete class.

To use a simple C++ console example of my point (only showing the .cpp files):

// example mainFile.cpp
#include <iostream>
#include "mainFile.h"
#include "functionsFile.h"
using namespace std;

void theMainFunction () {
    int resultBeforeAltering = 100;
    // alterTheResult() = simple inline function call I'm referring to
    cout << "The result is " << alterTheResult(resultBeforeAltering);
}

.

// example functionsFile.cpp - could contain many similar functions
#include "functionsFile.h"

int alterTheResult (int resultToAlter) {
    int alteredResult;
    if (resultToAlter < 100) {
        alteredResult = resultToAlter * 2;
    } else {
        alteredResult = resultToAlter * 3;
    }
    return (alteredResult);
}

Is there an equivalent approach to do alterTheResult() in Obj-C (assuming mainFunction() was an Obj-C method)?

I’ve seen reference to functions within Obj-C, but they seem to be C functions being referred to. C functions are not what I’m asking about here.

Thanks in advance, answers much appreciated.

Answer 1

Yes, the way to inline is to use C or C++ inlining — that’s perfectly legal (for C++, that will require compiling as ObjC++). An ObjC method will never be inlined (until LLVM produces a JIT compiler =p).

If you simply want to organize methods in another file, you may want to try an ObjC category:

// NSString_MONStuff.h
@interface NSString (MONStuff)
- (BOOL)mon_isPalindrome;
@end

// NSString_MONStuff.m    
@implementation NSString (MONStuff)
- (BOOL)mon_isPalindrome { return ...; }
@end

Again, those will not be inlined.

You can also use C or C++ external functions or classes instead of categories for organization – the benefit is speed, size, reduced dependencies, and safety. The choice is yours, but there’s no way to inline an objc method (it’s a very dynamic langauge).