ios - 找不到成员(member)申请

Question

无法应用脉冲，在xcode6.1 osx操场上出现错误“找不到成员applyimpulse”。

码:

func spawnSand() {

    let sand: SKSpriteNode = SKSpriteNode(imageNamed: "sand")
    sand.position = CGPoint(x: random(min:0 , max: scene.size.width), 
    y: scene.size.height - sand.size.height)

    sand.physicsBody = SKPhysicsBody(circleOfRadius: sand.size.width/2)
    sand.physicsBody!.restitution = 0.9
    sand.physicsBody!.density = 20.0
sand.name = "sand"
scene.addChild(sand)
}

func shake() {

    scene.enumerateChildNodesWithName("sand") { node, _ in
    node.physicsBody.applyImpulse(
      CGVector(dx:0 , dy: random(min: 20 ,max:40))
    )
    }
   }

Answer 1

node.physicsBody返回一个可选。使用前将其拆开

例如

if let SKPhysicsBody body = node.physicsBody {  
    body.applyImpulse( ... )
}