C++ Code in Objective-C for iOS

Question

Schleife.h

#ifndef __CPlusPlusTest__Schleife__
#define __CPlusPlusTest__Schleife__

#include <iostream>
class Schleife;
#endif /* defined(__CPlusPlusTest__Schleife__) */

Schleife.cpp

#include "Schleife.h"

class Schleife
{
public:
    int addition(int,int);

private:
    int ergebnis;
};


int Schleife::addition(int a,int b)
{
    ergebnis = a +b;
    return ergebnis;
}

ViewController.h

#import <UIKit/UIKit.h>

#import "Schleife.h"

@interface ViewController : UIViewController

@end

ViewController.mm

#import "ViewController.h"



@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
     Schleife *schleife = new Schleife();
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

Whats Wrong?

I got the Error Message: "ViewController.mm:22:31: Allocation of incomplete type 'Schleife'"

I don't understand what I did wrong. I want just implement C++ Code in my App. So I started with a easy example but it doesn't work... Can you help me? I know its maybe a easy Questions but I can't find the mistake...

i'm not sure but maybe you should put Schleife class declaration into Schleife.h? — Andrey Chernukha
– Andrey Chernukha, Commented Apr 2, 2014 at 6:52
I'm actually sure that without seeing the declaration of that class, neither Objective-C++ nor plain old C++ would be able to compile the new () call nor access any methods of the C++ class. This is nothing particular to Objective-C. That's what header files are for. — gnasher729
– gnasher729, Commented Apr 2, 2014 at 7:01

remudada · Accepted Answer · 2014-04-02 07:15:17Z

2

Schleife.h should have this code instead of the cpp file

class Schleife
{
public:
    int addition(int,int);

private:
    int ergebnis;
};

you will also need to include #include "Schleife.h" in your ViewController.mm

edited Apr 2, 2014 at 7:15

answered Apr 2, 2014 at 6:52

remudada

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6 Comments

J0k3R Over a year ago

but How i can use this return in my ObjC Code? int ergebnis = schleife::addition(10, 20); NSLog(@"%d",Ergebnis); i got this error Message: ViewController.mm:23:20: Use of undeclared identifier 'schleife'; did you mean 'Schleife'? and ViewController.mm:23:30: Call to non-static member function without an object argument

remudada Over a year ago

You can safely use this in your mm file, there should be no issues. What you need to do is use the mm file as a bridge between the cpp and the m world.

J0k3R Over a year ago

like a bridge? but How i get the cpp Types convert to ObjC Types

remudada Over a year ago

Primitive types can convert. the Classes do not convert at all. let me try to elaborate further in my answer

remudada Over a year ago

Looking at your code, you are missing #include "Schleife.h" in your mm file

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