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Duckwit
Member
Still plowing through my Obj-C book and coming across 'Factory Methods' it made me wonder for sec about the init method.
If you do say '[SomeClass new]', does it called the 'init' method automatically or is it a replacement for using 'new'.
Such as '[SomeClass init]' instead of, 'new' ?
codeman9
Member
This link may help: http://stackoverflow.com/questions/719877/use-of-alloc-init-instead-of-new-objective-c
@ Duckwit
I wouldn't say it's hidden. More like alloc is a class method in NSObject and since most classes are at some point a subclass of NSObject you will be able to use the alloc class method.
You could specify your own alloc (rarely needed though) if you don't create the alloc class method then inheritance comes into play (actually polymorphism if we want to be more specific).
Duckwit
Member
Thanks for the specific answers guys, and @Lam It's all clear now. I think :)
Also just wondering, as @toadkick said, 'new' is a replacement for '[[SomeClass alloc] init], right?
But can you call just like -
SomeClass *class = [SomeClass init];
-Will it allocate properly like that, do I need to use [[SomeClass alloc] init], OR can I have an 'alloc' IN my init method?
Well this line:
SomeClass *class = [SomeClass init]Would mean that you want to call an 'init' class method (needs a + in the method signature). But init is an instance method so that won't work.
[[SomeClass alloc]init] works because alloc returns an instance. For example you could separate this call.
SomeClass *theInstance = [SomeClass alloc];
theInstance = [theInstance init];So you have to just make sure you fully understand the difference between an 'instance' method and a 'class' method.
Blue Ether
Member
Not sure about "new," but calling "alloc" puts a retain on the object (regardless of calling init).
If you look at the source, or have made your own (as I frequently do), you'll see that most convenience methods (node, sprite.., etc) are simply calling:
[[[obj alloc] init...] autorelease];
The autorelease counteracts the retain put on the object by alloc.
Edit: @duckwit: If you think init is a class method, then I think you don't actually understand the difference between a class method and an instance method.
@Birkemose
This is what the NSObject reference says:
Special Considerations
If you are using managed memory (not garbage collection), this method retains the object before returning it. The returned object is not autoreleased. The invoker of this method is responsible for releasing the returned object, using either release or autorelease.
So that would make it the exact same as alloc/init, no?
*I hate memory management*
I had that messed up, and I am pretty sure now, that I retain more than I release.
On the other hand. One of the benefits of preloading everything and not destroying and creating along the way, is that I can retain an object 10 times, and it will make no difference.
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