gistfile1.txt

import UIKit

class Foo {
    var bar: Int
    
    init(bar: Int) {
        self.bar = bar
    }
}

struct K {
    static let x = Foo(bar: 1)
}

let y = Foo(bar: 1)

func change(_ foo: Foo, to: Int) {
    foo.bar = to
}

change(y, to: 3)
change(K.x, to: 3)

print("y \(y.bar)") // prints y 3
print("K.x \(K.x.bar)") // prints K.x 3