ios - 在 SpriteKit 中检查节点和实例类型之间的碰撞

Question

我正在尝试在我的游戏中测试子弹和特定类型的砖 block 之间的碰撞，这是一款打砖 block 类型的游戏。当子弹击中砖 block 时，砖 block 就会被移除。我可以测试任何砖 block 和子弹之间的碰撞，并将它们移走。但我无法让特定类型的砖 block 之间发生碰撞，然后移除该砖 block 。

这是我的 Brick.h 类

#import <SpriteKit/SpriteKit.h>

typedef enum : NSUInteger {
    // Normal Bricks
    Blue = 1,
    LightBlue = 2,
    DarkBlue = 3,
    Green = 4,
    LightGreen = 5,
    DarkGreen = 6,
    Grey = 7,
    DarkGrey = 8,
    Pink = 9,
    LightPink = 10,
    Purple = 11,
    LightPurple = 12,
    DarkPurple = 13,
    Red = 14,
    DarkRed = 15,
    Orange = 16,
    Gold = 17,
    Yellow = 18,
    Teal = 19,
    Brown = 20,
} BrickType;

static const uint32_t BRICK_CATEGORY = 0x1 << 2;

@interface XSBrick : SKSpriteNode

@property (nonatomic) BrickType type;
@property (nonatomic) BOOL indestructible;
@property (nonatomic) BOOL spawnsExtraBall;
@property (nonatomic) BOOL givesExtraLife;
@property (nonatomic) BOOL enlargePaddle;
@property (nonatomic) BOOL spawnsTwoOrThreeExtraBalls;
@property (nonatomic) BOOL makesBallSlow;
@property (nonatomic) BOOL makesBallFast;
@property (nonatomic) BOOL bullets;

-(instancetype)initWithType:(BrickType)type;
-(void)hit;

@end

Brick.m 类

#import "XSBrick.h"

@implementation XSBrick
{
    SKAction *_brickSmashSound;
}

#pragma mark - Load Bricks
-(instancetype)initWithType:(BrickType)type
{
    switch (type) {
        // Normal Bricks
        case Blue:
            self = [super initWithImageNamed:@"BrickBlue"];
            break;

        case LightBlue:
            self = [super initWithImageNamed:@"BrickLightBlue"];
            break;

        case DarkBlue:
            self = [super initWithImageNamed:@"BrickDarkBlue"];
            break;

        case Green:
            self = [super initWithImageNamed:@"BrickGreen"];
            break;

        case DarkGreen:
            self = [super initWithImageNamed:@"BrickDarkGreen"];
            break;

        case LightGreen:
            self = [super initWithImageNamed:@"BrickLightGreen"];
            break;

        case Grey:
            self = [super initWithImageNamed:@"BrickGrey"];
            break;

        case DarkGrey:
            self = [super initWithImageNamed:@"BrickDarkGrey"];
            break;

        case Pink:
            self = [super initWithImageNamed:@"BrickPink"];
            break;

        case LightPink:
            self = [super initWithImageNamed:@"BrickLightPink"];
            break;

        case Purple:
            self = [super initWithImageNamed:@"BrickPurple"];
            break;

        case LightPurple:
            self = [super initWithImageNamed:@"BrickLightPurple"];
            break;

        case DarkPurple:
            self = [super initWithImageNamed:@"BrickDarkPurple"];
            break;

        case Red:
            self = [super initWithImageNamed:@"BrickRed"];
            break;

        case DarkRed:
            self = [super initWithImageNamed:@"BrickDarkRed"];
            break;

        case Orange:
            self = [super initWithImageNamed:@"BrickOrange"];
            break;

        case Gold:
            self = [super initWithImageNamed:@"BrickGold"];
            break;

        case Yellow:
            self = [super initWithImageNamed:@"BrickYellow"];
            break;

        case Teal:
            self = [super initWithImageNamed:@"BrickTeal"];
            break;

        case Brown:
            self = [super initWithImageNamed:@"BrickBrown"];
            break;

        default:
            self = nil;
            break;
    }

    return self;
}

在 MyScene.m 中，didBeginContact。这有效，但会移除子弹击中的任何类型的砖 block

// Collision between bullets and bricks
    if (firstBody.categoryBitMask == BRICK_CATEGORY && secondBody.categoryBitMask == BULLET_CATEGORY) {
        [firstBody.node removeFromParent];
        [secondBody.node removeFromParent];
    }

我已经尝试过这个，但 Xcode 给了我一个关于 SKNode 和 NSUInteger 之间比较的警告，所以它不起作用。

// Collision between bullets and bricks
    if (firstBody.categoryBitMask == BRICK_CATEGORY && secondBody.categoryBitMask == BULLET_CATEGORY) {
        if (firstBody.node == LightBlue) {
            [firstBody.node removeFromParent];
        }
        [secondBody.node removeFromParent];
    }

我还尝试创建 Brick 的实例，然后对其进行测试，但这也不起作用。

// Collision between bullets and bricks
    if (firstBody.categoryBitMask == BRICK_CATEGORY && secondBody.categoryBitMask == BULLET_CATEGORY) {
        XSBrick *LightBlueBrick = [[XSBrick alloc]initWithType:LightBlue];
        if (firstBody.node == LightBlueBrick) {
            [firstBody.node removeFromParent];
        }
        [secondBody.node removeFromParent];
    }

我已经从事这个工作有一段时间了，现在正试图让它发挥作用。另外，我对 iOS 开发还很陌生，因此我们将不胜感激。

编辑:

我试过你的答案，rickster，但它抛出了一个错误，“2014-07-02 09:13:52.527 Brick Breaker[44129:60b] -[SKSpriteNode type]: unrecognized selector sent to instance 0x12145a2a0”。但我确实使用您提供的一些代码让它工作。

// Collision between bullets and bricks
if (firstBody.categoryBitMask == BRICK_CATEGORY && secondBody.categoryBitMask == BULLET_CATEGORY) {
    XSBrick *brick = nil;
    SKNode *bullets = nil;
    if ([firstBody.node isKindOfClass:[XSBrick class]]) {
        brick = firstBody.node;
        bullets = secondBody.node;
        if (brick.type == LightBlue) {
            [firstBody.node removeFromParent];
        }
        else if (brick.type == Blue) {
            [firstBody.node removeFromParent];
        }
    }
    [secondBody.node removeFromParent];
}

现在可以了。它会检测到击中的砖 block 类型，然后移除该砖 block 。如果它不在我的 if 语句中，它就不会被删除，这正是我想要的方式。非常感谢您的帮助!!

Answer 1

if (firstBody.node == LightBlue) 不起作用，因为您正在将节点(对象指针)与枚举值(整数)进行比较。您需要比较相同类型的值才能使相等比较具有任何有用的意义。

if (firstBody.node == LightBlueBrick) 不起作用，因为您正在针对您在那里创建的 XSBrick 实例进行测试。你已经在 didBeginContact 中，所以有一个节点已经存在并参与了冲突——如果你创建一个新节点，则保证该节点不是已经存在的节点。您只需要检查碰撞中每个节点的属性，找出它是哪个节点或哪种节点。

您已经有一个 if 语句来测试 firstBody.categoryBitMask 是否与您使用的砖 block 值匹配。如果您确定该值仅 用于砖 block ，您可以安全地假设firstBody.node 指向XSBrick 的一个实例。 (不过，安全的做法是使用 isKindOfClass 来确定。)

要让编译器调用XSBrick 方法，您需要将firstBody.node 转换为该类类型。然后您可以检查您在 XSBrick 上定义的 type 属性。

最后，SpriteKit 不保证接触处理程序中物体的顺序，因此砖头和子弹发生碰撞的第一个物体不一定总是砖头。

这些是解决此问题所需的要素。将它们放在一起，这是您的联系人处理程序的示例实现:

- (void)didBeginContact:(SKPhysicsContact *)contact {
    // If we expect more than one kind of collision, check that first
    if (contact.bodyA.categoryBitMask | contact.bodyA.categoryBitMask == BRICK_CATEGORY | BULLET_CATEGORY)
        // We know it's a brick/bullet collision, sort out which body is which
        XSBrick *brick = nil;
        SKNode *bullet = nil;
        if ([contact.bodyA.node isKindOfClass:[XSBrick class]]) {
            brick = contact.bodyA.node;
            bullet = contact.bodyB.node;
        } else  {
            brick = contact.bodyB.node;
            bullet = contact.bodyA.node;
        }

        // Now, check the type of brick
        if (brick.type == LightBlue) {
            // Do whatever with light blue bricks
        } else {
            // Do whatever with other kinds of bricks
        }
    }
}