NSMutableArray中的lastObject是否返回对象的副本?

问题描述

我有一段与此代码有关的问题

I have a question related to this piece of code

NSNumber *lastObject = [self.myStack lastObject];

if(lastObject){
    [self.myStack removeLastObject];
}

return [lastObject doubleValue];

令我惊讶的是，尽管被删除，lastObject仍在内存中.这是怎么回事?是lastObject返回对象的副本吗?

I am surprised that the lastObject is still in memory despite getting removed.How is this happening? Is it that lastObject returns a copy of the object?

推荐答案

否，它不是副本，而是自动发布的.它将在不久的将来发布.

No, it's not a copy, it's just autoreleased. It will be released in the near future.

要弄清-在[self.myStack removeLastObject]上，该对象会立即发送到release，但是您从[self.myStack lastObject]获得了一个自动释放的指针，因此该数组不是该对象的最后所有者.

to clarify - on [self.myStack removeLastObject], the object is sent release immediately, but you got an autoreleased pointer from [self.myStack lastObject] so the array is not the last owner of the object.

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