什么是“超级”在Objective-C？ （自我！=超级）？ [英] What is "super" in Objective-C? ( self != super )?
问题描述
我已经阅读了下面的问题，故事 SEEMS 简单：
I've read the question below, and the story SEEMS simple:
然而...
- (id) init
{
NSLog(@"self=%p, super=%p", self, super);
}
打印出self = 0xa83dc50，super = 0xbfffe8d0。地址不是相同的???！？！？
That prints out "self=0xa83dc50, super=0xbfffe8d0". The addresses are NOT THE SAME???!?!?
第二个地址看起来像是特殊价值或其他东西。这是什么意思？
That second address seems like a "special value" or something. What does it mean?
感谢bbum指出这个值是编译器用来实现的特殊结构的堆栈地址超级行为。
Thanks to bbum for pointing out that this value is the stack address of a special struct used by the compiler to implement the "super" behavior.
我可以调用[super init]和电话似乎有效，或至少没有爆炸......不是立刻。使用EXC_BAD_ACCESS调用[（（id）0xbfffe8d0）init]失败。
I can call [super init] and the call seems to work, or at least, nothing explodes ... not immediately. Calling [((id)0xbfffe8d0) init] fails hard with EXC_BAD_ACCESS.
然后有真正的WEIRD部分.....
我有一段代码，由于没有可解释的原因抛出NSGenericException：集合在被枚举时被突变异常。在一个DIFFERENT对象（基本上是一个包含指向NSEnumerator的指针的包装器）中，注释掉对[super init]的调用会导致异常不会发生。如果可以的话，我会为这个心灵弯曲者的答案提出一个$$$奖励。
Then there is the REALLY WEIRD part..... I've got a piece of code that for no explainable reason throws a "NSGenericException: collection was mutated while being enumerated" exception. Inside a DIFFERENT object (basically a wrapper that has a pointer to the NSEnumerator), commenting out the call to "[super init]" causes the exception to not happen. If I could, I'd put out a $$$ reward for an answer to THAT mind-bender.
id sups =（id）0xbfffe8d0......这也导致收藏被修改。 ...... WTF？好的，所以我发布第二个问题就是那个bizzariotity ...
"id sups = (id)0xbfffe8d0" ... that also leads to "collection is modified." ... WTF? Ok, so I'm posting a 2nd question for that bizzariotity ...
我原来带着其中一个问题来到这里奇怪的症状错误，结果证明完全不相关（典型的这类事情）：将地址转换为（id）是否有副作用???地址0xbfffe8d0特殊吗？ （已修复：问题出在_NSCallStackArray上）
但是，该行上方的内容仍然有效，响应仍然很好。如果你想更深入地了解ObjC，请阅读它。
However, the content above the line is still valid, and the response still excellent. Read it if you want to understand ObjC just a little bit deeper.
推荐答案
你正在弄乱窗帘后面的男人和他正在惩罚你...... :)
You are messing with the man behind the curtain and he is punishing you for it... :)
super 真的是编译魔术。当你说 [super doSomething] 时，编译器将发出对 objc_msgSendSuper（）的调用，而不是 objc_msgSend（）。大部分时间 - 有一些特殊情况。
super is a bit of compiler magic, really. When you say [super doSomething], the compiler will emit a call to objc_msgSendSuper() instead of objc_msgSend(). Most of the time -- there are some special cases.
一般来说，你应该将 super 视为只有方法调用的目标。它永远不应该被存储在任何地方，并且永远不应被视为任何但的目标表达式用于消息传递。
In general, you should treat super as only a target for method calls. It should never be stored anywhere and should never be considered anything but that target expression for messaging.
事实上，使用<$ c $涉及存储的超级可能会被编译器标记。
In fact, uses of super that involve storage should likely be flagged by the compiler.
就你的错误而言，这听起来很糟糕内存损坏，过度释放和/或并发。您需要提供更多与枚举相关的代码和其他相关代码以进一步推断。
In terms of your bug, that sounds an awful lot like there is either corruption of memory, an over-release, and/or concurrency going on. You'll need to provide more code related to the enumeration and other relevant code to deduce further.
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