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最近一直在自学objective-c，以便学习Cocos2d。

开始了一个新项目，通过经典的坠落宝石俄罗斯方块游戏自学基础知识。我采取的第一步是使用编辑 > 重构为 ARC 启用项目，并选择模板中的最后 4 个文件。

到目前为止，已经能够通过子类化 CCSprite 添加具有动态颜色精灵的单个 gem，并在它从顶部掉落的同时沿着 XCoordinates 移动它。这些宝石被赋予一个 gemPos 位置——例如 5,3——以便我稍后实现匹配方法。

在测试项目一段时间后，当一些块相互堆叠时，我会收到 EXC_BAD_ACCESS 警告。如果启用了 ARC，我对为什么会发生这种情况感到困惑。

我笨拙的代码如下（省略了 .h 文件）：

默认的 helloworld 层：

-(id) init
    {

        if( (self=[super init]) ) {

            oldGems = [[NSMutableArray alloc]init];

            [self setIsTouchEnabled:YES];

            [self newGem];

            [self scheduleUpdate];

        }
        return self;
    }

    - (void)registerWithTouchDispatcher
    {
        [[[CCDirector sharedDirector] touchDispatcher] addTargetedDelegate:self priority:0 swallowsTouches:YES];
    }

    - (BOOL)ccTouchBegan:(UITouch *)touch withEvent:(UIEvent *)event
    {
        CGPoint touchLocation = [self convertTouchToNodeSpace:touch];
        oldPos = touchLocation;
        return TRUE;
    }

    - (void)ccTouchMoved:(UITouch *)touch withEvent:(UIEvent *)event
    {
        CGPoint touchLocation = [self convertTouchToNodeSpace:touch];
        [self updateXCoord:(CGPoint)touchLocation];
    }

    - (void)updateXCoord:(CGPoint)touchLocation
    {


        CGPoint distance = ccpSub(touchLocation, oldPos);
        float xDistance = distance.x;

        if (abs(xDistance) >= 36) {
            if (touchLocation.x > oldPos.x) {
                [_thisGem setPosition:ccp([_thisGem position].x + 36, [_thisGem position].y)];
                [_thisGem setGemPos:ccp([_thisGem gemPos].x+1,[_thisGem gemPos].y)];
                NSLog(@"The gem position is %@", NSStringFromCGPoint([_thisGem gemPos]));
                oldPos = touchLocation;
            } else {
                [_thisGem setPosition:ccp([_thisGem position].x - 36, [_thisGem position].y)];
                [_thisGem setGemPos:ccp([_thisGem gemPos].x-1,[_thisGem gemPos].y)];
                NSLog(@"The gem position is %@", NSStringFromCGPoint([_thisGem gemPos]));
                oldPos = touchLocation;
            }
        }


    }

    - (void)newGem
    {
        if (_thisGem) {
            PCGem *oldGem = _thisGem;
            NSLog(@"Old gem position at %@", NSStringFromCGPoint([oldGem gemPos]));
            [oldGems addObject:oldGem];
        }

        _thisGem = [[PCGem alloc] initWithGemColor];
        [_thisGem setPosition:ccp(160, 450)];
        [self addChild:_thisGem];
        [_thisGem setGemPos:ccp(4,10)];

        NSLog(@"Gem added with %@ color", [_thisGem gemColorName]);
    }

    - (void)update:(ccTime)dt
    {

        if ([_thisGem gemPos].y > 0)  {

            [self spaceBelowOccupied];

            [_thisGem setPosition:ccp([_thisGem position].x, [_thisGem position].y-1)];
            [_thisGem setGemPos:ccp([_thisGem gemPos].x, floor([_thisGem position].y / 36))];

        } else {
            [self newGem];
        }
    }

    - (void)spaceBelowOccupied
    {    
            for (PCGem *occupiedTile in oldGems) {
                if (CGRectIntersectsRect(occupiedTile.boundingBox, _thisGem.boundingBox)) {
                    NSLog(@"Collision detected!");
                    [self newGem];
                }
            }
    }

还有我笨拙的 PCGem 课：

    - (id)initWithGemColor
    {
        if ((self = [super initWithFile:@"gemGS.png"])) {


            NSArray *gemColorList = [NSArray arrayWithObjects:(NSString *)@"blue", (NSString *)@"red", (NSString *)@"green", nil];

            NSInteger randColor = arc4random_uniform(3);

            switch (randColor) {
                case 0:
                {
                    [self setGemColorName:[gemColorList objectAtIndex:0]];

                    ccColor3B gemColorRGB = {0,0,255};
                    [self setColor:gemColorRGB];
                    break;
                }
                case 1:
                {
                    [self setGemColorName:[gemColorList objectAtIndex:1]];

                    ccColor3B gemColorRGB = {255,0,0};
                    [self setColor:gemColorRGB];            
                    break;
                }
                case 2:
                {
                    [self setGemColorName:[gemColorList objectAtIndex:2]];

                    ccColor3B gemColorRGB = {0,255,0};
                    [self setColor:gemColorRGB];
                    break;
                }
            }

        }

        return self;

    }

这让我想到了另一个问题，我似乎找不到答案。在启用 ARC 的 Cocos2d 项目的示例中，我看到了使用的节点便捷方法，当然是 alloc]init]autorelease]。但是我认为您不能将 Autorelease 与 ARC 一起使用，这会导致崩溃吗？这是如何运作的？

对我的困境有什么想法吗？非常感谢澄清:)

干杯，

阿德里安

4

1 回答 1

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我认为这可能是由于在枚举数组时编辑数组引起的。在您的更新函数中，您调用 spaceBelowOccupied：

- (void)spaceBelowOccupied
{    
        for (PCGem *occupiedTile in oldGems) {
            if (CGRectIntersectsRect(occupiedTile.boundingBox, _thisGem.boundingBox)) {
                NSLog(@"Collision detected!");
                [self newGem];
            }
        }
}

那么如果 newGem 在你的 for 循环中被调用并且这个循环成功：

if (_thisGem) {
        PCGem *oldGem = _thisGem;
        NSLog(@"Old gem position at %@", NSStringFromCGPoint([oldGem gemPos]));
        [oldGems addObject:oldGem];
    }

然后你在枚举它的同时将一个对象添加到一个数组中。因此，将您的 spaceBelowOccupied 更改为此并查看它是否有效：

 - (void)spaceBelowOccupied
{    
        for (PCGem *occupiedTile in [oldGems copy]) {
            if (CGRectIntersectsRect(occupiedTile.boundingBox, _thisGem.boundingBox)) {
                NSLog(@"Collision detected!");
                [self newGem];
            }
        }
}

这样你就可以复制 oldGems 来枚举，一旦你完成它就会自动发布。

于 2013-06-02T04:11:01.293 回答