Call an Objective C instance method from a c++ class?

Question

How can I call an Objective C instance method from a c++ class? In TestApp.cpp I would like to call updateUI in TestDelegate.mm

TestDelegate.h

#include "cinder/app/CinderView.h" #include "TestApp.h" #import <Cocoa/Cocoa.h> @interface TestDelegate : NSObject <NSApplicationDelegate> { IBOutlet CinderView *cinderView; IBOutlet NSWindow *window; TestApp *mApp; } @property (assign) IBOutlet NSWindow *window; - (IBAction)subdivisionSliderChanged:(id)sender; - (void)updateUI; @end

TestDelegate.mm

#include "cinder/Cinder.h" #import "TestDelegate.h" @implementation TestDelegate @synthesize window; - (void)dealloc { [super dealloc]; } - (void)applicationDidFinishLaunching:(NSNotification *)aNotification { mApp = new TestApp; mApp->prepareLaunch(); mApp->setupCinderView( cinderView, cinder::app::RendererGl::create() ); mApp->launch(); } - (void)updateUI { //Set new values... } @end

TestApp.h

#pragma once #include "cinder/app/AppCocoaView.h" class TestApp : public cinder::app::AppCocoaView { public: void setup(); void draw(); };

TestApp.cpp

#include "TestApp.h" #include "cinder/gl/gl.h" using namespace ci; using namespace ci::app; void TestApp::setup() { //Set values //Call updateUI method in TestDelegate.mm } void TestApp::draw() { }

is this not a duplicate? stackoverflow.com/questions/6958685/… Once you're in a .mm, all C++ and Obj-C work equally. — Almo
– Almo, Commented Mar 3, 2014 at 18:21

NSGod · Accepted Answer · 2014-03-03 19:24:39Z

Something like the following ought to work:

TestDelegate.mm

#include "cinder/Cinder.h" #import "TestDelegate.h" @implementation TestDelegate - (void)applicationDidFinishLaunching:(NSNotification *)aNotification { // mApp = new TestApp; // mApp->prepareLaunch(); // mApp->setupCinderView( cinderView, cinder::app::RendererGl::create() ); // add the following line mApp->m_TestDelegate = self; // mApp->launch(); } @end

TestApp.h

#pragma once #include "cinder/app/AppCocoaView.h" @class TestDelegate; class TestApp : public cinder::app::AppCocoaView { public: void setup(); void draw(); TestDelegate *m_TestDelegate; };

TestApp.cpp -> renamed to TestApp.mm

#include "TestApp.h" #include "cinder/gl/gl.h" #import "TestDelegate.h" using namespace ci; using namespace ci::app; void TestApp::setup() { //Set values //Call updateUI method in TestDelegate.mm [this->m_TestDelegate updateUI]; }

Note: this code was written in a browser, and the Objective-C++ stuff I've done doesn't use ARC, so if it gives any warnings/errors, let me know and I'll update the code accordingly.

Awesome thanks, working great, as I expected I was trying all the wrong ways to go about it. One thing: Xcode gives a warning in in TestApp.mm Instance method '-updateUI' not found (return type defaults to 'id')
@davivid: Are you sure you included the #import "TestDelegate.h" line in your TestApp.mm file?

Chuck · Accepted Answer · 2014-03-03 18:27:33Z

To call an instance method, you need an instance. Once your C++ code has a pointer to an instance of the class, you can just change the file to Objective-C++ and send a message like normal.

Could you give more details as to how I can create the instance and pointer within the framework shown?

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