如果我在-init中什么也不做，是否与仅调用[MyClass alloc]一样? [英] If I do nothing in -init, is it the same as just calling [MyClass alloc]?

问题描述

如果我有一个NSObject子类，该子类要么没有-init方法，要么根本没有在-init中执行任何操作，那么通过以下两种方式创建的实例之间是否有任何区别:

If I have an NSObject subclass which either has no -init method or simply does nothing in -init, is there any difference between an instance created these two ways:

MyClass *instance = [MyClass alloc];
MyClass *instance = [[MyClass alloc] init];

我的意思是在-init中什么也不做"

By "does nothing in -init" I mean

- (id)init {
    self = [super init];
    if (self) {
    }
    return self;
}

由于NSObject的-init方法本身不执行任何操作，因此我看不到有什么区别，但是当然建议您必须调用-init进行正确的准备一个对象.

Since NSObject's -init method itself does nothing, I can't see there being any difference, but of course the advice is that you must call -init to properly prepare an object.

以下是

Here's the snippet from NSObject's -init method which got me wondering about this:

NSObject类中定义的init方法不进行初始化；它只是返回自我.

The init method defined in the NSObject class does no initialization; it simply returns self.

推荐答案

如果我有一个NSObject子类，该子类要么没有-init方法，要么 在-init中什么都不做， 实例创建了以下两种方式:

If I have an NSObject subclass which either has no -init method or simply does nothing in -init, is there any difference between an instance created these two ways:

MyClass *instance = [MyClass alloc];
MyClass *instance = [[MyClass alloc] init];

技术上，没有区别.

但这并不意味着您出于各种原因应该使用裸露的+alloc来创建实例，.

But that doesn't mean you should use a bare +alloc to ever create an instance for a variety of reasons.

首先，它是事物的主体. Objective-C编码标准说，在 +alloc之后应始终跟随-init .

First, it is the principal of the thing. Objective-C coding standards say +alloc should always be followed by -init.

第二，这全都与一致性和代码维护有关.当您将MyClass重构为某个类的子类，其中指定的初始化程序实际上很重要时，会发生什么?发生的是令人讨厌的，很难弄清的错误.

Secondly, it is all about consistency and code maintenance. What happens when you refactor MyClass to be a subclass of some class where the designated initializer is actually critical? A nasty, hard to figure out, bug is what happens.

相关性，请注意，出于类似原因，几乎不建议使用+new.它使重构变得乏味(该死！也必须拆开该呼叫站点！)，而便利性因素却极小.

Of relevance, note that the use of +new has been all but deprecated for a similar reason. It makes refactoring tedious (dammit! gotta break apart THIS call site, too!) and the convenience factor is exceedingly minimal.

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