spritekit nodeAtPoint的交集

Question

我正在尝试检测两个精灵（shipLaser和baddie）相交的坐标，然后在该位置创建一个新的精灵（speedPowerUp）。以下是我尝试对nodeAtPoint进行的操作，但它正在运行，然后在两个精灵相交时崩溃。

for (SKSpriteNode *baddie in _baddies)
{

    baddie.name = @"baddie1";

    if (baddie.hidden) {
        continue;
    }
    for (SKSpriteNode *shipLaser in _shipLasers){
        if (shipLaser.hidden) {
            continue;
        }

        if ([shipLaser intersectsNode:baddie]) {
            shipLaser.hidden = YES;
            baddie.hidden = YES;
            [shipLaser nodeAtPoint:*(_itemDrop)];
            NSLog(@"You just destroyed a baddie");
            _score = _score + 10;
            _scoreLabel.text = [NSString stringWithFormat:@"%i", _score];
            if (_score == 10)
            {

                _speedPowerUp.hidden = NO;
                _speedPowerUp.position = *(_itemDrop);
                [self addChild:_speedPowerUp];

            }