If I do nothing in -init, is it the same as just calling [MyClass alloc]?

Question

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];

By "does nothing in -init" I mean

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

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.

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

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

Answer 1

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];

Technically, there is no difference.

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

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

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.

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.

Answer 2

No, it's not and you're not doing nothing, you're calling [super init] and that does a lot to initialize your superclasses up until NSObject.