憤怒的小鳥在精靈套件Xcode中的彈弓

Question

我使用精靈套件是，我需要添加一個憤怒的小鳥彈弓等向球的Xcode做一個遊戲，我不知道我怎樣才能運用它

import SpriteKit 
class GameScene: SKScene { 
override func didMoveToView(view: SKView) {let sprite = SKSpriteNode(imageNamed:"ball") 
    sprite.position = CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame)) 
    sprite.physicsBody = SKPhysicsBody(circleOfRadius: 20) 
    sprite.size.height = 50 
    sprite.size.width = 50 
    sprite.physicsBody?.affectedByGravity = true 
    sprite.physicsBody!.allowsRotation = false 
    sprite.physicsBody!.friction = 0 
    sprite.physicsBody!.restitution = 1 
    sprite.physicsBody!.linearDamping = 0 
    sprite.physicsBody!.angularDamping = 0 
    self.addChild(sprite) 

    // 1. Create a physics body that borders the screen 
    let borderBody = SKPhysicsBody(edgeLoopFromRect: self.frame) 
    // 2. Set the friction of that physicsBody to 0 
    borderBody.friction = 0 
    // 3. Set physicsBody of scene to borderBody 
    self.physicsBody = borderBody 

Answer 1

只要給球一個衝動，gravitiy會完成剩下的工作。