spritekitでプレイヤーが移動した時に、壁に当たったら動かない様にしたい

どうやってもプレイヤーが壁を押してしまいます、どうすれば、skactionなどで移動したプレイヤー（RPG想定）が、壁に当たった時にそこで止まる様な仕様を実装できますか？

画面のピンク色の長方形の部分のNodeは川になっていて、歩行中のプレイヤーが歩けないようにしたくて、テクスチャーは入れずにダイナミックを入れ、Massを100くらいにしたりして、プレイヤーが接触したらそこで止まる様にしたいのですが、何をどうしても、SKActionやCGvecterで移動したプレイヤーがこのNodeを押してしまいます。
PindにしてもプライヤーのMassやdentityを0にしても押してしまいます。プレイヤーの動きをはねのける様な、そんな壁の存在が欲しいのです。

import SpriteKit
import GameplayKit

class GameScene: SKScene,SKPhysicsContactDelegate {

    var textureSide:[SKTexture] = []
    var textureUp:[SKTexture]   = []
    var textureDown:[SKTexture] = []

    var upB:SKSpriteNode!
    var downB:SKSpriteNode!
    var rightB:SKSpriteNode!
    var leftB:SKSpriteNode!

    var playerposition = CGPoint(x: 0, y: 0)

    var yellow:SKSpriteNode!

    var player:SKSpriteNode!
    var wall:SKSpriteNode!

    var rightpoti = true

    enum direction {
        case right
        case left
        case up
        case down    
    }

    override func didMove(to view: SKView) {

        physicsWorld.gravity = CGVector(dx: 0, dy: 0)

        wall = self.childNode(withName: "wall") as! SKSpriteNode
        wall.physicsBody?.usesPreciseCollisionDetection = true
        wall.zPosition = 5

        player = SKSpriteNode(imageNamed: "walkman8")
        player.position = playerposition
        player.physicsBody?.usesPreciseCollisionDetection = true
        player.zPosition = 2
        player.setScale(2)
        player.physicsBody = SKPhysicsBody(rectangleOf: player.frame.size)
        player.physicsBody?.categoryBitMask = 1
        player.physicsBody?.collisionBitMask = 0
        player.physicsBody?.contactTestBitMask = 0
        player.physicsBody?.density = 1
        player.physicsBody?.mass = 1
        player.physicsBody?.restitution = 2
        addChild(player)

        upB = self.childNode(withName: "upB") as! SKSpriteNode
        downB = self.childNode(withName: "downB") as! SKSpriteNode
        rightB = self.childNode(withName: "rightB")  as! SKSpriteNode
        leftB = self.childNode(withName: "leftB")  as! SKSpriteNode

        yellow = self.childNode(withName: "yellow") as! SKSpriteNode
        yellow.position = CGPoint(x: -0, y: -600)

        let atras = SKTextureAtlas(named: "walker")

        for i in 1...3{
            textureSide.append(atras.textureNamed("walkman" + String(i)))
        }

        for i in 6...7{
            textureDown.append(atras.textureNamed("walkman" + String(i)))
        }

        for i in 8...10{
            textureUp.append(atras.textureNamed("walkman" + String(i)))
        }

        let animation = SKAction.animate(with: textureDown, timePerFrame: 0.6 )
        player.run(SKAction.repeatForever(animation))
    }

    func didBegin(_ contact: SKPhysicsContact) {
        print("bodyA:\(String(describing: contact.bodyA.node?.name))")

        if contact.bodyA == wall  {
            player.run(SKAction.rotate(byAngle: 30, duration: 1))
        }
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        for touch in touches {
            let location = touch.location(in: self)

            if self.atPoint(location) == upB {
                movePlayer(Direction: .up)
            }
            if self.atPoint(location) == downB {
                movePlayer(Direction: .down)
            }
            if self.atPoint(location) == leftB {
                movePlayer(Direction: .left)
            }
            if self.atPoint(location) == rightB {
                movePlayer(Direction: .right)
            }
        }
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    }

    override func update(_ currentTime: TimeInterval) {
    }

    func movePlayer(Direction:direction){
        player.physicsBody?.velocity = CGVector(dx: 0, dy: 100)
    }
}