Object only initialisable through factory method (Objective-c)

Question

I am trying to create an object only instantiatable through a factory method. I prevented init being used by throwing an exception (see Creating a class with no init method). However this meant that I had to create a new method secretInit to use in the factory method.

//Factory method
- (URLReqs *)buildURLReq:(NSString *)location
{
    URLReqs *tmp=[[URLReqs alloc] secretInit];
    tmp.str=location
    return tmp;
}

- (id) secretInit{
    return [super init];
}

This method is messy and while we can avoid declaring secretInit in the header file, someone could still access it. Is there a nicer solution?

One idea is to try calling init on the super object of URLReqs directly rather than creating a function to do it.

Answer 1

The solution is to use a category on your object to hide the secret initialization method.

Private Methods through categories

What goal are you trying to accomplish? There might be a better solution than this.

Answer 2

It only exposes it if it's referenced in the header file.

No, wait. I should state that another way. There's no better way to hide it than to not declare it in the header file. Private methods don't exist in Objective-C.