Reuse same sprite node within multiple scenes in sprite kit using Swift

Question

I create sprite node in my GameScene as the following. I would like to reuse createNodeA1 or nodeA1 in other SKScene. How can I do that?

import SpriteKit

class GameScene: SKScene {

var nodeA1: SKNode!

required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
}

override init(size: CGSize) {
    super.init(size: size)

    // Add sprite node to the scene        
    nodeA1 = createNodeA1()
    addChild(nodeA1)

    }
}

// Create dot 1
func createNodeA1() -> SKNode {
    let spriteNode = SKNode()
    spriteNode.position = CGPointMake(CGRectGetMidX(self.frame)/1.5, CGRectGetMidY(self.frame)/2.0)

    let sprite = SKSpriteNode(imageNamed: "dot_1")
    sprite.zPosition = 3.0
    sprite.name = "A1_Broj"
    spriteNode.addChild(sprite)

    return spriteNode
}

}

Answer 1

There is a few ways to do this.

You could subclass your other scenes to be subclass of the scene with the loadNode function which gives those scenes access to that function.

I asked a question about this last year

Swift multiple level scenes

Another way that might be a bit easier if you are not comfortable with scene subclassing is to just create a subclass of the node itself.

So you create a class

enum EnemyType {
   case Normal
   case Special
} 


class NodeA1: SKSpriteNode {

   init(imageNamed: String, enemyType: EnemyType) {
      let texture = SKTexture(imageNamed: imageNamed)

      if enemyType == .Normal {
           super.init(texture: texture, color: SKColor.clearColor(), size: texture.size())
      else {
         // other init
      }

     self.zPosition = 1
     self.name = ""
     // add physics body, other properties or methods for the node

    }
}

Than in your SKScenes you can add the node in the init method like so

  nodeA1 = NodeA1(imageNamed: "ImageName", enemyType: .Normal)
  nodeA1.position = ....
  addChild(nodeA1)

this way ever scene where you add the node will use the subclass and therefore include all the properties, set up etc for that node. Another benefit with subclassing is that you could loop through all your nodes using

self.enumerateChildNodesWithName...

and than call custom methods on all nodes.

If you want to subclass your scenes than you would create your baseScene

 class BaseScene: SKScene {

     // set up all shared stuff in didMoveToView
     // have your node function here 
     // touches began
     // physics word and contact collision 
     // all other stuff that needs to be shared between all level scenes

   }

Than your subsequent level scenes would look something like this

  class Level1Scene: BaseScene {

     override func didMoveToView(view: SKView) {
           super.didMoveToView(view) // This lines imports all stuff in BaseScene didMoveToView


       // do level 1 specific setUps.
       // you can call any function or property from BaseScene, e.g the loadNode function.
  }

You than load you level scenes as usual, e.g you transition to level 1 scene and it will automatically use/have access to all the superclass methods and sprites (BaseScene). So you never call baseScene directly, its gets called automatically.

This applies for other methods in baseScene too, so say you have a Update method in BaseScene.

 override func update(currentTime: CFTimeInterval) {.... }

This will work across all your level scenes which are subclasses of BaseScene.

But what happens if you need to add some specific stuff to the update method only relevant in 1 level scene and not all level scenes? It would be the same process, you create a new update func in the LevelScene and call super.

 override func update(currentTime: CFTimeInterval) {
     super.update(currentTime) // this calls the baseScene Update method

    /// specific stuff for that level only
  }

Super simply means the super class of the currentScene, which is BaseScene if the scene is a subclass of it.

Is this helping?

Answer 2

This is additional answer information in terms of subclass of the baseScene. We can create node1thru node10 all in baseScene. Then in Leve1Scene which is subclass of the baseScene, all we have to do is in didMoveToView function state node1.position = CGPointMake(....) for each node that we need in Level1Scene where we would specify node's position. If we do not need to load all of the 10 nodes in Level1Scene, for example, let's say we don't need to load to the scene node10 we can simply in didMoveToView function just state node10.removeFromParent() and this node will not be loaded to Level1Scene but rest of 9 nodes will. Note that this example uses only 10 nodes, but you can go with any number of nodes in your baseScene. This way of subclassing will save you a lot repeatable code in subclasses.