Mixing Objective-C and C++

Question

I'm trying to mix Objective-C with C++. When I compile the code, I get several errors.

A.h

#import <Cocoa/Cocoa.h> #include "B.h"  @interface A : NSView {     B *b; }  -(void) setB: (B *) theB;  @end 

A.m

#import "A.h"  @implementation A  - (id)initWithFrame:(NSRect)frame {     self = [super initWithFrame:frame];     if (self) {         // Initialization code here.     }     return self; }  - (void)drawRect:(NSRect)dirtyRect {     // Drawing code here. }  -(void) setB: (B *) theB {     b = theB; }  @end 

B.h

#include <iostream>  class B {      B() {         std::cout << "Hello from C++";     }  }; 

Here are the errors:

/Users/helixed/Desktop/Example/B.h:1:0 /Users/helixed/Desktop/Example/B.h:1:20: error: iostream: No such file or directory /Users/helixed/Desktop/Example/B.h:3:0 /Users/helixed/Desktop/Example/B.h:3: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'B' /Users/helixed/Desktop/Example/A.h:5:0 /Users/helixed/Desktop/Example/A.h:5: error: expected specifier-qualifier-list before 'B' /Users/helixed/Desktop/Example/A.h:8:0 /Users/helixed/Desktop/Example/A.h:8: error: expected ')' before 'B' /Users/helixed/Desktop/Example/A.m:26:0 /Users/helixed/Desktop/Example/A.m:26: error: expected ')' before 'B' /Users/helixed/Desktop/Example/A.m:27:0 /Users/helixed/Desktop/Example/A.m:27: error: 'b' undeclared (first use in this function) 

Answer 1

You need to name your .m files .mm. And you will be able to compile C++ code with Objective-C.

So, following your example, your AView.m file should be named AView.mm. It's simple as that. It works very well. I use a lot of std containers (std::vector, std::queue, etc) and legacy C++ code in iPhone projects without any complications.

Answer 2

Never mind, I feel stupid. All you have to do is rename AView.m to AView.mm so the compiler knows it's Objective-C++, and it compiles without a problem.