SKSpriteNode是SKNode的子节点,放置在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…
删除必须同时发生在SKSpriteNode父级和数组中.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然后从SKNode父项删除2 /,则执行完成块.
>如果是逆序,1 / SKNode父级则为2 /数组,则不执行完成块.
为什么会这样？
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")})
}
将显示完成消息.
现在,如果在从theGrid操作中删除removeFromParent之前,如下所示,则不会执行完成：
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}),])
从
SKAction Reference：
An SKAction object is an action that is executed by a node in the
scene (SKScene)…When the scene processes its nodes,actions associated with those
nodes are evaluated.
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,从场景中删除节点,永远不会调用runBlock操作(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.
为安全起见,我建议将removeFromParent调用移动到完成块.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")
}
}
TL; DR序列没有完成,因此序列的完成块不会被调用.
