Class method to return autoreleased object

Question

I have been following the iPhone development videos on iTunes U and so far so good. I think I understood things well enough.

The thing is that on the examples they provide they never create custom class methods just like those that you use on some Foundation classes (like [NSString string]) so I'm not sure as to how I should go about creating my own class method to return an autoreleased instance of my class.

I do know how to create a retained object using an instance method but I'd rather use a class method because I prefer it, I'm just not sure if this implementation would be the most appropriate to return an autoreleased object:

+ (PhotoViewController*)initWithImageView:(UIImageView*)imageView
{
    PhotoViewController *toreturn = [[PhotoViewController alloc] init];
    toreturn.imageview = imageView;
    [toreturn autorelease];
    return toreturn;
}

Thanks a lot for any help you may provide.

Answer 1

A class method can return either a retained or autoreleased object as you wish, and your code returns an autoreleased object perfectly appropriately.

However you should probably name your method differently. Since your method begins with init, that implies it is initialising an alloced object (and should therefore be an instance method rather than a class method). I'd suggest naming the method photoViewControllerWithImageView: if it's going to return an autoreleased object.

Also, I'd probably write it as return [toreturn autorelease]; but I guess that's a style preference of mine.

Answer 2

I think it's a good practice to check whether toreturn is nil or not before accessing imageview property.