为什么一些对象在使用objective-c之前不需要初始化？ [英] Why do some objects not need to be initialized before use in objective-c?

问题描述

为什么一些对象在使用objective-c之前不需要初始化？
例如为什么这个 NSDate * today = [NSDate date]; legal？

Why do some objects not need to be initialized before use in objective-c? For example why is this NSDate *today = [NSDate date]; legal?

推荐答案

它们在 date 方法中初始化。这是在Objective-C中创建自动释放对象的常用方法。

They are initialized within the date method. This is a common way to create autoreleased objects in Objective-C. Allocators of that form are called convenience allocators.

要了解更多信息，请阅读Apple的Cocoa Core Competencies文档中关于对象创建的工厂方法段落： http://developer.apple.com/library/mac /#documentation/General/Conceptual/DevPedia-CocoaCore/ObjectCreation.html

To learn more about that, read the "Factory Methods" paragraph in Apple's Cocoa Core Competencies document about Object Creation: http://developer.apple.com/library/mac/#documentation/General/Conceptual/DevPedia-CocoaCore/ObjectCreation.html

要为您自己的类创建方便分配器，请实现一个类方法，命名为你的类（无前缀）。例如：

To create convenience allocator for you own classes, implement a class method, named after your class (without prefix). e.g.:

@implementation MYThing
...

+ (id)thing
{
  return [[[MYThing alloc] init] autorelease];
}

...
@end

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