精灵套件：不能阻止两个物体碰撞

Question

我有玩家类别，敌人类别和墙壁类别。我希望我的敌人类别能够穿过我的墙壁类别，我希望我的玩家类别在撞墙时停止。我让我的玩家停在墙上，但我也无法阻止我的敌人与我的墙碰撞。我不确定为什么......这是我的代码：

 static const int playerCategory =3;
 static const int wallCategory = 2;
 static const int enemyCategory = 1;

敌人代码：

 self.physicsBody.dynamic = YES;
 self.physicsBody.restitution = 0.2;
 self.physicsBody.allowsRotation = NO;
 self.physicsBody.categoryBitMask = enemyCategory;
 self.physicsBody.collisionBitMask =  playerCategory;
 self.physicsBody.contactTestBitMask =  playerCategory;

墙代码：

 wallRight.physicsBody.dynamic = NO;
 wallRight.physicsBody.allowsRotation = NO;
 wallRight.physicsBody.categoryBitMask = wallCategory;
 wallRight.physicsBody.collisionBitMask =  playerCategory;
 wallRight.physicsBody.contactTestBitMask =  playerCategory;

玩家代码：

self.physicsBody.dynamic = YES;
self.physicsBody.restitution = 0.2;
self.physicsBody.allowsRotation = NO;
self.physicsBody.categoryBitMask = playerCategory;
self.physicsBody.collisionBitMask = wallCategory | enemyCategory;
self.physicsBody.contactTestBitMask = wallCategory | enemyCategory;

我错过了什么？