i fail with isJumping = true for my mobile game

hey i want my character to add a jumping animation to my doodlejump clone style. I think I know how to specify the sprites but I fail with the query isJumping = true. can someone help me?

the coin provides the platform on which the player lands the ground is only at the start

//  GameScene.swift
//  megaJump
//
//  Created by Dennis Sergel on 26.06.23.
//

import Foundation
import SpriteKit

class GameScene: SKScene, SKPhysicsContactDelegate{
    
    let background = SKSpriteNode(imageNamed: "background")
    let player = SKSpriteNode(imageNamed: "Monster2")
    let ground = SKSpriteNode(imageNamed: "ground")
    let coin = SKSpriteNode(imageNamed: "coin")
    
    
    
   
    enum bitmasks: UInt32 {
        case player = 0b1
        case coin = 0b10
    }
    
    
    override func didMove(to view: SKView) {
        self.size = CGSize(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)
        
        self.anchorPoint = .zero
        
        background.position = CGPoint(x: size.width / 2, y: 1060)
        background.zPosition = 1
        background.setScale(1.3)
        addChild(background)
        
        physicsWorld.contactDelegate = self
        
        ground.position = CGPoint(x: size.width / 2, y: 80)
        ground.zPosition = 5
        ground.setScale(2.5)
        ground.physicsBody = SKPhysicsBody(rectangleOf: ground.size)
        ground.physicsBody?.isDynamic = false
        ground.physicsBody?.affectedByGravity = false
        addChild(ground)
        
        
        
        player.position = CGPoint(x: size.width / 2, y: 150)
        player.zPosition = 80
        player.setScale(0.14)
        player.physicsBody = SKPhysicsBody(circleOfRadius:
                                            player.size.height / 2)
        player.physicsBody?.isDynamic = false // later is true
        player.physicsBody?.restitution = 1
        player.physicsBody?.friction = 0
        player.physicsBody?.angularDamping = 0
        player.physicsBody?.categoryBitMask = bitmasks.player.rawValue
        player.physicsBody?.collisionBitMask = 0
        player.physicsBody?.contactTestBitMask = bitmasks.coin.rawValue
        addChild(player)
        
        animatePlayer(isJumping: true)
        makeCoin()
        
    }
    func animatePlayer (isJumping: Bool){
        if isJumping {
            player.texture = SKTexture(imageNamed: "monster")
        }else{
            player.texture = SKTexture(imageNamed: "Monster2")
        }
    }
        
    
        
        
   
    
    

    
    func didBegin(_ contact: SKPhysicsContact) {
        let contactA: SKPhysicsBody
        let contactB: SKPhysicsBody
        
        if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask{
            contactA = contact.bodyA // player
            contactB = contact.bodyB // Coin
        } else {
            contactA = contact.bodyB // player
            contactB = contact.bodyA // coin
        }
        
        if contactA.categoryBitMask == bitmasks.player.rawValue && contactB.categoryBitMask == bitmasks.coin.rawValue{
            
            if player.physicsBody!.velocity.dy < 0 {
                player.physicsBody?.velocity = CGVector(dx: player.physicsBody!.velocity.dx, dy: 120)
            }
        }
    }
   
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        for touch in touches {
            
            
            let location = touch.location(in: self)
            
            player.position.x = location.x
        }
    }
    
    
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        player.physicsBody?.isDynamic = true
        player.physicsBody?.applyImpulse(CGVector(dx: 0, dy: 120))
    }
    
    func makeCoin() {
        coin.position = CGPoint(x: size.width / 2, y: 150)
        coin.zPosition = 5
        coin.setScale(0.14)
        coin.physicsBody = SKPhysicsBody(rectangleOf: coin.size)
        coin.physicsBody?.isDynamic = false
        coin.physicsBody?.allowsRotation = false
        coin.physicsBody?.affectedByGravity = false
        coin.physicsBody?.categoryBitMask = bitmasks.coin.rawValue
        coin.physicsBody?.collisionBitMask = 0
        coin.physicsBody?.contactTestBitMask = bitmasks.player.rawValue
        addChild(coin)
    }
}