How to create a Swift object in Objective-C?

Question

If you define a swift class like this

@objc class Cat {

}

In swift you can just do

var c = Cat()

But how

Answer 1

You can declare +alloc in a dummy category (don't need to implement it):

@interface Cat (Alloc)
+ (instancetype)alloc;
@end

and then you can use regular alloc-init on it:

Cat *cat = [[Cat alloc] init];

all without needing to change the Swift code.