iPhone：（id）copyWithZone：（NSZone *）区域：什么是“区域”对于？ [英] iPhone : (id)copyWithZone:(NSZone *)zone : what is "zone" for?

问题描述

在类中实现此NSCopying方法以启用复制时，区域参数的用途是什么？
如果我设置一个新对象，我不需要用allocWithZone分配它，因为一个分配就够了......我很困惑......

When implementing this method of NSCopying in a class to enable copy, what is the zone param use ? If I set a new object, I do not need to alloc it with allocWithZone as an alloc is just enough... I'm confused...

推荐答案

这是旧时代的遗物，我们有多个区域可供分配。这些天，所有应用程序只有一个区域，所有分配都在这里，但是 NSZone 类仍然存在，编写的代码太多依赖于 + allocWithZone：作为进行更改的基本分配方法。

It's a relic from the old days, where we had multiple "zones" to allocate in. These days, all apps only have a single zone where all allocations are made, but the NSZone class still exists and far too much code is written to depend on +allocWithZone: being the fundamental allocation method to make the change.

简而言之，您可以完全忽略 NSZone 结构，并且唯一理由关注 + allocWithZone：是否需要覆盖它。与 -copyWithZone：类似，您可以忽略该区域。如果您愿意，可以调用 + allocWithZone：传入相同的区域，但不会有任何区别。

In short, you can ignore the NSZone struct in its entirety, and the only reason to care about +allocWithZone: is if you need to override it. Similarly with -copyWithZone:, you can just ignore the zone. If you so desire, you can call +allocWithZone: passing in the same zone, but it won't make any difference.

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