Objective-C call class method on Class variable

Question

I need to call a class method on a variable of type Class, which I know holds a subclass of a base class, MyBaseClass...

- (void)foo:(Class)clazz {
  // Now i want to call +myClassMethod on clazz
}

I don't know if this is actually possible. If it is, is there a safer way to guarantee that clazz is actually a subclass of MyBaseClass?

Thanks in advance

Answer 1

You can use -respondsToSelector:, just like you would with any Objective-C object. You can also use +isSubclassOfClass: to test whether the class is a subclass of another class.

- (void)foo:(Class)clazz 
{
    if ([clazz respondsToSelector:@selector(myClassMethod)])
    {
        [clazz myClassMethod];
    }
    else
    {
        // clazz does not implement that class method.
    }

    if ([clazz isSubclassOfClass:[MyBaseClass class]])
    {
        [clazz myClassMethod];
    }
    else
    {
        // clazz is not a subclass of MyBaseClass.
    }
}

Answer 2

Try this:

if ( [clazz isKindOfClass:[MyBaseClass class]] ) {
  [clazz myClassMethod];
}