Accessing global variable in Swift

Question

Given this sample Swift code:

var a = 10;

func foo() -> Int {
    var a = 20;
    return a;
}

How can function foo get access to global

Answer 1

 func foo(bar:Any) -> Int {
        let a = 20
        if bar is Bar {
            let c = bar as? Bar
            return c!.a
        }
        return a
  }