Question

SKSpriteNode是SKNode的孩子，并存放在SKSpriteNode数组中以用于存储目的。

使用动画删除此SKSpriteNode。在此动画结束时，执行完成块以执行某些语句...

必须在SKSpriteNode父级和数组中进行删除。根据这两个删除的顺序，结果是否正确：

如果从1 /数组中删除SKSpriteNode，则从SKNode父项删除{/>，则执行完成块。
如果逆序，1 / SKNode父级则为2 /数组，则不执行完成块。

为什么会出现这种情况？

for position in listOfPositions {

   theSprite:SKSpriteNode = theGrid[position]

   /// the SKSpriteNode referenced by theSprite :
   /// - belongs to an array of SKSpriteNode: theGrid
   /// - belongs to a SKNode: theGameLayer
   ///
   /// In other words this SKSpriteNode is referenced twice
   ///

   let theActions = SKAction.sequence([
      /// Some actions here
      /// ...

      /// Remove theSprite from the Grid
      /// - position is an instance of a structure of my own
      /// - theGrid is accessed via a subscript
      ///
      SKAction.runBlock({self.theGrid[position] = nil}),

      /// remove theSprite from it's parent
      SKAction.removeFromParent(),
   ])

   theSprite.runAction(theActions,completion:{NSLog("Deleted")})
}

显示完成消息。

现在，如果在removeFromParent操作移除之前放置theGrid，请执行以下操作：

let theActions = SKAction.sequence([
   /// Some actions here
   /// ...

   /// remove theSprite from it's parent
   SKAction.removeFromParent(),

   /// remove theSprite from the Grid
   SKAction.runBlock({self.theGrid[position] = nil}),
])

Answer 1

来自SKAction Reference：

SKAction对象是由节点中的节点执行的操作 scene（SKScene）...当场景处理其节点时，与之相关的动作评估节点。

换句话说，当且仅当该节点在场景中时，才运行节点的动作。通过调用removeFromParent，您从场景中删除节点，永远不会调用runBlock动作（因为节点不再在场景中），因此序列永远不会完成。由于序列没有完成，因此不会调用完成块。

出于安全考虑，我建议将removeFromParent调用移至完成块。这样的事情感觉更安全：

for position in listOfPositions {

   let theSprite: SKSpriteNode = theGrid[position]

   /// the SKSpriteNode referenced by theSprite :
   /// - belongs to an array of SKSpriteNode: theGrid
   /// - belongs to a SKNode: theGameLayer
   ///
   /// In other words this SKSpriteNode is referenced twice
   ///

   let theActions = SKAction.sequence([
      /// Some actions here
      /// ...

      /// Remove theSprite from the Grid
      /// - position is an instance of a structure of my own
      /// - theGrid is accessed via a subscript
      ///
      SKAction.runBlock({self.theGrid[position] = nil})
   ])

   theSprite.runAction(theActions) {
      /// remove theSprite from it's parent
      /// Might need to weakly reference self here
      theSprite.removeFromParent(),
      NSLog("Deleted")
   }
}

<强> TL; DR
序列没有完成，因此序列的完成块不会被调用。

SKAction runAction不执行完成块

1 个答案: