http://hub.ae/blog/2014/03/26/soft-body-physics-jellyusing-spritekit/

jellyusing-spritekit

import SpriteKit

class GameScene: SKScene {
    
    private var mainCircle: SKSpriteNode!
    
    override func didMoveToView(view: SKView) {
       
        physicsBody = SKPhysicsBody(edgeLoopFromRect: self.frame)
        
        createBall()
    }
    
    override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
    
        if let touch: UITouch = touches.first as? UITouch {
        
            mainCircle.physicsBody?.applyImpulse(CGVector(dx: 0, dy: 1000))
        }
    }

    private func createBall() {
    
        mainCircle = SKSpriteNode(color: SKColor.whiteColor(),
            size: CGSize(width: 10, height: 10))
        mainCircle.position = CGPoint(x: 200, y: 280)
        mainCircle.name = "player"
        
        mainCircle.physicsBody = SKPhysicsBody(circleOfRadius: 10)
        mainCircle.physicsBody?.dynamic = true
        mainCircle.physicsBody?.affectedByGravity = false
        mainCircle.physicsBody?.mass = 4.0
        
        addChild(mainCircle)
        
        for(var loop: Int = 0; loop < 6; loop++) {
        
            let angle: CGFloat = ((CGFloat(M_PI) * 2)/6) * CGFloat(loop)
            
            var x_offset: CGFloat = cos(angle)
            var y_offset: CGFloat = sin(angle)
            
            x_offset *= 20
            y_offset *= 20
            
            let point: SKSpriteNode = SKSpriteNode(color: UIColor.grayColor(),
                size: CGSize(width: 10, height: 10))
            point.position = CGPoint(x: mainCircle.position.x + x_offset,
                y: mainCircle.position.y + y_offset)
            point.name = "samllcircle"
            
            point.physicsBody = SKPhysicsBody(circleOfRadius: 10)
            point.physicsBody?.dynamic = true
            point.physicsBody?.affectedByGravity = true
            point.physicsBody?.mass = 2/6
            
            addChild(point)
            
            let joint: SKPhysicsJointSpring = SKPhysicsJointSpring.jointWithBodyA(
                    mainCircle.physicsBody,
                    bodyB: point.physicsBody,
                    anchorA: mainCircle.position,
                    anchorB: point.position)
            joint.damping = 2.0
            joint.frequency = 9.0
            
            physicsWorld.addJoint(joint)
        }
    }
}