Question

Is there a way in Objective-C to store an object/class in a variable to be passed to alloc/init somewhere else?

For example:

UIViewController = foo
foo *bar = [[foo alloc] init]

I’m trying to create a system to dynamically create navigation buttons in a separate class based on the current view controller. I can pass ‘self’ to the method, but the variable that results does not allow me to alloc/init. I could always import the .h file directly, but ideally I would like to make reusing the code as simple as possible. Maybe I’m going about this the wrong way?

Answer 1

Not sure to understand your question, but if you are trying to create a fresh instance of the same class as another instance, you can do something like that:

id foo; // an actual instance of any class

id bar = [[[foo class] alloc] init]; // another instance

If foo isn’t declared as id, you can even use a shortcut: [[foo.class alloc] init] or even shorter: [foo.class new].

You can also use either the class object:

id foo;
Class fooClass = [foo class];

id bar = [[fooClass alloc] init];

Or the class name:

id foo;
NSString* fooClassName = NSStringFromClass( [foo class] );

id bar = [[NSClassFromString( fooClassName ) alloc] init];