我有一个游戏，我正在将身体从屏幕上弹开。我想检测这些身体何时与屏幕的边缘接触（仍然让身体通过屏幕离开屏幕），我已经实现了一切，但它仍然无法正常工作..这是我的代码：
游戏场景.h
typedef NS_OPTIONS(uint32_t, FAPhysicsCategory) {
FAWallCategory = 1 << 0,
FABottomWallCategory = 1 << 1,
FAAnimalCategory = 1 << 2,
};
GameScene : SKScene <SKPhsyicsContactDelegate>
游戏场景.m
-(void)setupWorldPhysics
{
// Set world gravity
self.physicsWorld.gravity = CGVectorMake(0.0, -5.0);
float bottomOffset = 400.0;
CGRect newFrame = CGRectMake(0, -bottomOffset, self.frame.size.width, self.frame.size.height + bottomOffset);
self.physicsBody = [SKPhysicsBody bodyWithEdgeLoopFromRect:newFrame];
self.physicsBody.categoryBitMask = FAWallCategory;
self.physicsBody.contactTestBitMask = FAAnimalCategory;
self.physicsBody.collisionBitMask = 0;
}
-(void)launchBody {
SKSpriteNode* animalSprite = [SKSpriteNode spriteNodeWithImageNamed:[animalImagesArray objectAtIndex:animalChoice]];
animalSprite.position = CGPointMake(self.size.width/2, -animalSprite.size.height);
animalSprite.physicsBody = [SKPhysicsBody bodyWithCircleOfRadius:25];
animalSprite.physicsBody.dynamic = YES;
animalSprite.physicsBody.allowsRotation = YES;
animalSprite.name = @"animalSprite";
animalSprite.physicsBody.categoryBitMask = FAAnimalCategory;
animalSprite.physicsBody.contactTestBitMask = FAWallCategory;
animalSprite.physicsBody.collisionBitMask = 0;
animalSprite.physicsBody.usesPreciseCollisionDetection = YES;
[self addChild:animalSprite];
}