Question

我有一个功能可以为我的场景添加被定时间隔调用的敌人

如何跟踪场景中的敌人数量以限制每个级别的敌人数量？

**在我的更新功能**

CFTimeInterval timeSinceLastEnemy = currentTime - self.lastEnemyUpdateTime;
self.lastEnemyUpdateTime = currentTime;
if (timeSinceLastEnemy > 1) { // more than a second since last update
    timeSinceLastEnemy = 1.0 / 60.0;
    self.lastEnemyUpdateTime = currentTime;
}

[self spwanEnemyWithTime:timeSinceLastEnemy];

**计时器和添加敌人的方法**

- (void)spwanEnemyWithTime:(CFTimeInterval)timeSinceLast {

    self.lastEnemySpawn += timeSinceLast;
    if (self.lastEnemySpawn > 0.6) {
        self.lastEnemySpawn = 0;
        [self spawnEnemy];
    }
}

-(void) spawnEnemy {

    SKSpriteNode *enemy = [SKSpriteNode spriteNodeWithImageNamed: enemySprite];

    int minX = 5;
    int maxX = self.frame.size.width;
    int rangeX = maxX - minX;
    int actualX = (arc4random() % rangeX) + minX;

    // Create the enemy slightly off-screen along the upper edge,

    enemy.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(enemy.size.height - 10 , enemy.size.width)]; 
    enemy.physicsBody.dynamic = YES;
    enemy.physicsBody.categoryBitMask = enemyCategory; 
    enemy.physicsBody.contactTestBitMask = bulletCategory; 
    enemy.physicsBody.collisionBitMask = 0;     

    // and along a random position along the X axis as calculated above
    enemy.position = CGPointMake(actualX, self.frame.size.height + enemy.size.height);
    [self addChild:enemy];
    enemy.xScale = 0.2;
    enemy.yScale = 0.2;
    enemy.zPosition = 4;

    // Create the actions
    SKAction * actionMove = [SKAction moveToY:(0 - enemy.size.height) duration:4];
    SKAction * actionMoveDone = [SKAction removeFromParent];
    [enemy runAction:[SKAction sequence:@[actionMove, actionMoveDone]]];
}

Answer 1

我承认我无法掌握你用双倍计时器做的事情，所以我会假设这部分按照你的意愿运作。对于敌人计数来说，这就像在你的spawnEnemy上增加一个计数器并在敌人从场景中移除自己时减少计数器一样简单吗？

你必须仔细检查我的Obj-c我有一段时间没用过它。

int enemyCount = 0;

-(void) spawnEnemy {

    enemyCount += 1

    ...

    // Create the actions
    SKAction *actionMove = [SKAction moveToY:(0 - enemy.size.height) duration:4];
    SKAction *actionMoveDone = [SKAction removeFromParent];
    SKAction *decrementCount = [SKAction runBlock: ^(void) {
        enemyCount -= 1;                           
    }];

    [enemy runAction:[SKAction sequence:@[actionMove, actionMoveDone, decrementCount]]];
}

仅供参考，您的方法中有拼写错误＆＃34; spwanEnemyWithTime＆＃34;

跟踪某个类别的SKNodes

1 个答案: