从NSArray检索类对象并添加到self [英] Retrieving Class Object from NSArray and adding to self

问题描述

您尝试从NSMutableArray检索特定类的对象，然后将其添加到self：例如：

Hi im trying to retrieve an object of a specific class from an NSMutableArray, and then add it to self: eg:

- (void) init{
     _Objects = [[NSMutableArray alloc]init];
     Psychicing *psy = [[Psychicing alloc]init];
     [psy startPsychic];
     [_Objects addObject: psy];
     [psy release];
}

这将创建一个Psychicing类的对象，然后运行[psy startPsychic]方法创建类对象的内部。然后我添加psy对象到_Objects NSMutableArray。

This creates an object of class Psychicing, then runs the [psy startPsychic] method to create the internals of the class object. Then I add the psy object to _Objects NSMutableArray.

-(void)startPsychic{
      id psychicParticle = [CCParticleSystemQuad ......]; //is Synthesised with (assign)
      //Other things are set here such as position, gravity, speed etc...
}

当在屏幕上检测到触摸时，我想从_Objects数组中获取psy对象并将其添加到self：这样的东西（虽然这会导致运行时错误） / p>

When a touch is detected on screen, I want to take the psy object from the _Objects array and add it to self: Something like this (Although this gives runtime error)

-(void) Touches.....{

     for (Psychicing *psy in _Objects){
          [self addChild: psy.psychicParticle];
     }
}

我希望我已经解释得很清楚，如果你需要更多的澄清让我知道。

所以基本上：

[MainClass Init] - > [Psychicing startPsychic] - > [MainClass add to array] - > [MainClass add to self]

I hope i have explained it clearly enough, if you need more clarification let me know.
So basically:
[MainClass Init] -> [Psychicing startPsychic] -> [MainClass add to array] -> [MainClass add to self]

推荐答案

我假设_Objects（它应该是一个小写的o遵守约定）存储对象除了Psychicing对象并且你试图在 - （void）Touches ...方法（也应该是小写）中拉出Psychicing对象。如果是，您可以：

I'm assuming the _Objects (which should be a lowercase o to follow conventions) is storing objects other than the Psychicing object and you're trying to pull just the Psychicing object out of it in the -(void)Touches... method (which also should be lowercase). If so, you could do:

for (id obj in _Objects)
{
  if ([obj isMemberOfClass:[Psychicing class]])
    [self addChild:obj.psychicParticle];
}

这将只导​​致数组中的Psychicing对象被添加为子自我。

That will cause only the Psychicing objects in the array to be added as a child to self.

看起来你有另一个错误，但如果你粘贴的代码是你的真正的代码。 init应定义为：

It looks like you do have another error though if the code you pasted in is your real code. Init should be defined as:

- (void) init{
     _Objects = [[NSMutableArray alloc]init];
     Psychicing *psy = [[Psychicing alloc]init];
     [psy startPsychic];
     [_Objects addObject: psy];
     [psy release];
}

<正如你写的，它是一个方法变量在init方法和泄漏。所以当你尝试访问_tools中的_Objects时，_Objects很有可能是nil。

with _Objects defined as an instance variable (or property) in the class's interface. As you wrote it, it's a method variable in the init method and is leaking. So when you try to access _Objects in -touches, _Objects is most likely nil.

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