A cocos2d-x code that cause crash on Android but not on iOS - cocos2d-x

Question

While porting an cocos2d-x project from iOS to Android, I found a problem that will cause crashing on Android but not on iOS, to show this problem, I made a small modification to the HelloWorld sample. To reproduce this problem, just press the close button on the bottom-right corner, on Android it will crash but not on iOS.
The code that cause the crashing is:
void TestNode::test()
{
// This will cause crash on Android, but OK on iOS
CCCallFunc *selector = CCCallFunc::create(this, callfunc_selector(TestNode::destroy));
this->runAction(selector);
// This is ok on both Android and iOS
// CCCallFunc *selector = CCCallFunc::create(scene_, callfunc_selector(HelloWorld::destroyNode));
// scene_->runAction(selector);
// This is ok on both Android and iOS
// destroy();
}
The complete code as the following:
HelloWorldScene.h
#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__
#include "cocos2d.h"
class TestNode : public cocos2d::CCNode {
public:
TestNode(cocos2d::CCLayer *scene);
~TestNode();
void test();
void destroy();
cocos2d::CCLayer *scene_;
cocos2d::CCSprite *sprite_;
};
class HelloWorld : public cocos2d::CCLayer
{
private:
TestNode *node_;
public:
// Here's a difference. Method 'init' in cocos2d-x returns bool, instead of returning 'id' in cocos2d-iphone
virtual bool init();
// there's no 'id' in cpp, so we recommend returning the class instance pointer
static cocos2d::CCScene* scene();
// a selector callback
void menuCloseCallback(CCObject* pSender);
// implement the "static node()" method manually
CREATE_FUNC(HelloWorld);
void destroyNode();
};
#endif // __HELLOWORLD_SCENE_H__
HelloWorldScene.cpp:
#include "HelloWorldScene.h"
#include "AppMacros.h"
USING_NS_CC;
TestNode::TestNode(cocos2d::CCLayer *scene):
scene_(scene)
{
sprite_ = CCSprite::create("CloseNormal.png");
sprite_->setPosition(ccp(200, 200));
scene_->addChild(sprite_, 255);
}
TestNode::~TestNode()
{
scene_->removeChild(sprite_, true);
scene_->removeChild(this, true);
CCLog("+++ ~TestNode");
}
void TestNode::test()
{
// This will cause crash on Android, but OK on iOS
CCCallFunc *selector = CCCallFunc::create(this, callfunc_selector(TestNode::destroy));
this->runAction(selector);
// This is ok on both Android and iOS
// CCCallFunc *selector = CCCallFunc::create(scene_, callfunc_selector(HelloWorld::destroyNode));
// scene_->runAction(selector);
// This is ok on both Android and iOS
// destroy();
}
void TestNode::destroy()
{
CCLog("+++ destroy");
delete this;
}
CCScene* HelloWorld::scene()
{
// 'scene' is an autorelease object
CCScene *scene = CCScene::create();
// 'layer' is an autorelease object
HelloWorld *layer = HelloWorld::create();
// add layer as a child to scene
scene->addChild(layer);
// return the scene
return scene;
}
// on "init" you need to initialize your instance
bool HelloWorld::init()
{
//////////////////////////////
// 1. super init first
if ( !CCLayer::init() )
{
return false;
}
CCSize visibleSize = CCDirector::sharedDirector()->getVisibleSize();
CCPoint origin = CCDirector::sharedDirector()->getVisibleOrigin();
/////////////////////////////
// 2. add a menu item with "X" image, which is clicked to quit the program
// you may modify it.
// add a "close" icon to exit the progress. it's an autorelease object
CCMenuItemImage *pCloseItem = CCMenuItemImage::create(
"CloseNormal.png",
"CloseSelected.png",
this,
menu_selector(HelloWorld::menuCloseCallback));
pCloseItem->setPosition(ccp(origin.x + visibleSize.width - pCloseItem->getContentSize().width/2 ,
origin.y + pCloseItem->getContentSize().height/2));
// create menu, it's an autorelease object
CCMenu* pMenu = CCMenu::create(pCloseItem, NULL);
pMenu->setPosition(CCPointZero);
this->addChild(pMenu, 1);
/////////////////////////////
// 3. add your codes below...
// add a label shows "Hello World"
// create and initialize a label
CCLabelTTF* pLabel = CCLabelTTF::create("Hello World", "Arial", TITLE_FONT_SIZE);
// position the label on the center of the screen
pLabel->setPosition(ccp(origin.x + visibleSize.width/2,
origin.y + visibleSize.height - pLabel->getContentSize().height));
// add the label as a child to this layer
this->addChild(pLabel, 1);
// add "HelloWorld" splash screen"
CCSprite* pSprite = CCSprite::create("HelloWorld.png");
// position the sprite on the center of the screen
pSprite->setPosition(ccp(visibleSize.width/2 + origin.x, visibleSize.height/2 + origin.y));
// add the sprite as a child to this layer
this->addChild(pSprite, 0);
node_ = new TestNode(this);
this->addChild(node_);
return true;
}
void HelloWorld::menuCloseCallback(CCObject* pSender)
{
// CCDirector::sharedDirector()->end();
if (node_) {
node_->test();
node_ = NULL;
}
//#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
// exit(0);
//#endif
}
void HelloWorld::destroyNode()
{
node_->destroy();
}

Answer 1

I don't know why this works on iOS but you should not do this anyway. When you run the code
CCCallFunc *selector = CCCallFunc::create(this, callfunc_selector(TestNode::destroy));
this->runAction(selector);
which calls the function
void TestNode::destroy()
{
CCLog("+++ destroy");
delete this;
}
you are destroying an object that the CCCallFunc action still keeps a pointer to. Then when the CCCallFunc object is destroyed, it runs the CC_SAFE_RELEASE macro which will call release on your TestNode object. However, by now that TestNode object is already deallocated and that is most likely the reason for your crash.