Question

我是Cocos2d的初学者，所以虽然这里有一些代码。有经验的人应该能够看到我在这里做错了什么。当我尝试在NSAssert类方法中获取作为子级添加到此图层的backgroundLayer实例时，它会在GameBackground class中的+(id)scene崩溃。崩溃导致它Nil（ GameBackground类。但是当我要求+(id)scene时，我想我用node方法初始化了它？但请纠正我，我的想法在这个问题上很模糊。

static GameLayer *sharedGameLayer = nil;
+(id) scene
{
    CCScene *scene = [CCScene node];

    //GameLayer* layer = [GameLayer node];
    //[scene addChild:layer];

    CCNode *backgroundLayer = [GameBackground node];
    [scene addChild:backgroundLayer z:1 tag:LayerTagBackgroundLayer];

    CCLayer *cocosObjectsLayer = [HelloWorldLayer node];
    [scene addChild:cocosObjectsLayer z:2 tag:LayerTagGameLayer];

    CCLayer *userTouchInterface = [GameUserTouchInteface node];
    [scene addChild:userTouchInterface z:3 tag:LayerTagUILayer];
    return scene;
}

// To access this scene: MultiLayerScene* sceneLayer = [MultiLayerScene sharedLayer];
+ (GameLayer *) sharedLayer
{
    NSAssert(sharedGameLayer = nil, @"sharedGameLayer not available.");
    //if (sharedGameLayer == nil) sharedGameLayer = [[GameLayer alloc] init];
    return sharedGameLayer;
}


-(id) init
{
    NSLog(@"init called");
    self = [super init];
    if (self)
    {
        NSAssert(sharedGameLayer == nil, @"another GameLayer is already in use!");
        sharedGameLayer = self;


        // uncomment if you want the update method to be executed every frame
        //[self scheduleUpdate];
    }
    return self;
}


// MultiLayerScene* sceneLayer = [MultiLayerScene sharedLayer];
// To access this scene: GameBackgroundLayer* backgroundLayer = [sceneLayer backgroundLayer];
-(GameBackground *) backgroundLayer
{
    CCNode *layer = [self getChildByTag:LayerTagBackgroundLayer];
    NSAssert([layer isKindOfClass:[GameBackground class]], @"%@: not a BackgroundLayer!", NSStringFromSelector(_cmd));
    return (GameBackground *)layer;
}

然后尝试从另一个类获取背景图层的实例：

    GameBackground *backgroundLayer = [GameLayer sharedLayer].backgroundLayer;
    [backgroundLayer runAction:sequence];

Answer 1

我猜测失败的断言是.-

NSAssert(sharedGameLayer = nil, @"sharedGameLayer not available.");

您将nil分配给sharedGameLayer而不是比较（==）。另外，您已经注释了设置sharedGameLayer的行。只是在这里猜测，但你可能想做这样的事情.-

+(id) scene
{
    CCScene *scene = [CCScene node];

    sharedGameLayer = [GameLayer node];
    [scene addChild:layer];

    return scene;
}

让static构造函数尽可能干净。

+ (GameLayer *) sharedLayer
{
    return sharedGameLayer;
}

-(id) init
{
    NSLog(@"init called");
    self = [super init];
    if (self)
    {
        CCNode *backgroundLayer = [GameBackground node];
        [self addChild:backgroundLayer z:1 tag:LayerTagBackgroundLayer];

        CCLayer *cocosObjectsLayer = [HelloWorldLayer node];
        [self addChild:cocosObjectsLayer z:2 tag:LayerTagGameLayer];

        CCLayer *userTouchInterface = [GameUserTouchInteface node];
        [self addChild:userTouchInterface z:3 tag:LayerTagUILayer];

        // uncomment if you want the update method to be executed every frame
        //[self scheduleUpdate];
    }
    return self;
}

在init方法中创建节点树，并将它们添加为根层（sharedGameLayer）的子节点而不是场景对象。

Cocos2d：按节点初始化图层 - 类为零

1 个答案: