Can objective-c code call swift extension on Class?

I found out that in Swift 4.0 I had to add @objc in front of my extension keyword in order for the Swift extension methods to become visible by an instance of the Objc class I was extending.

In short:

File configuration setup:

CustomClass.h
CustomClass.m
CustomClassExtension.swift

In CustomClassExtension:

@objc extension CustomClass
{
    func method1() 
    {
        ...
    }
}

In my AppDelegate.m:

self.customClass = [[CustomClass alloc] init];
[self.customClass method1];

https://stackoverflow.com/questions/27097688/can-objective-c-code-call-swift-extension-on-class