How to animate a sprite based on its velocity?

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Xcode

sprites

Swift

Hey I have this project in which the player is supposed to go up like Mega Jump and I want to animate the player so that when it goes left or right or down it changes its image according to it. Any ideas how I can achieve this? This is my code where I create the player.

func createPlayer() -> SKNode {

    let playerNode = SKNode()
    playerNode.position = CGPoint(x: self.size.width / 2, y: 80.0)
    var spriteTexture = SKTexture(imageNamed: "IMAGE")
    var sprite = SKSpriteNode(texture: spriteTexture)

    if (playerNode.physicsBody?.velocity.dx < 0) && (playerNode.physicsBody?.velocity.dy > 0) {

        sprite = SKSpriteNode(imageNamed: "LEFT")
        let frames = [
            SKTexture(imageNamed: "LEFT"),
        ]
        let duration = 0.5
        let move = SKAction.animateWithTextures(frames, timePerFrame:0.25)
        let wait = SKAction.waitForDuration(duration)
        let rest = SKAction.setTexture(frames[0])
        let sequence = SKAction.sequence([wait, move, wait, rest])
        sprite.runAction(sequence)


    } else if (playerNode.physicsBody?.velocity.dx > 0) && (playerNode.physicsBody?.velocity.dy > 0){

        sprite = SKSpriteNode(imageNamed: "RIGHT")
        let frames = [
            SKTexture(imageNamed: "RIGHT"),
        ]
        let duration = 0.5
        let move = SKAction.animateWithTextures(frames, timePerFrame:0.25)
        let wait = SKAction.waitForDuration(duration)
        let rest = SKAction.setTexture(frames[0])
        let sequence = SKAction.sequence([wait, move, wait, rest])
        sprite.runAction(sequence)

    }
    playerNode.addChild(sprite)



    playerNode.physicsBody = SKPhysicsBody(circleOfRadius: sprite.size.width / 2)
    playerNode.physicsBody?.dynamic = false
    playerNode.physicsBody?.allowsRotation = false
    playerNode.physicsBody?.restitution = 1.0
    playerNode.physicsBody?.friction = 0.0
    playerNode.physicsBody?.angularDamping = 0.0
    playerNode.physicsBody?.linearDamping = 0.0
    playerNode.physicsBody?.usesPreciseCollisionDetection = true
    playerNode.physicsBody?.categoryBitMask = CollisionCategoryBitmask.Player
    playerNode.physicsBody?.collisionBitMask = 0
    playerNode.physicsBody?.contactTestBitMask = CollisionCategoryBitmask.Star | CollisionCategoryBitmask.Platform | CollisionCategoryBitmask.Monster


    return playerNode
} 

I don't know if im on track or doing it all wrong, I am still learning sprite kit and swift. But if anyone could help me achieve this I would appreciate it! Thank you in advance