struct Foo {
    var bar:Dictionary<String, Any> = [:]
}

extension Foo {
    init(json: [String: Any]) {
        if let bar = json["bar"] {
            self.bar = bar as! Dictionary<String, Any>
        }
    }
}

let param:Dictionary<String, Any> = ["bar": 12]
let options = Foo(param)

if (options.bar != [:]) {
    // ok, the bar is set - do something
}

Binary operator '!=' cannot be applied to operands of type 'Dictionary<String, Any>' and '[AnyHashable : Any]'

if let bar = json["bar"] {
        self.bar = bar as! Dictionary<String, Any>
    }

extension Foo {
    init(json: [String: Any]) {

        if let _ = json["bar"] {

            self.bar = json
        }
    }
}

let param:Dictionary<String, Any> = ["bar": 12]
 let options = Foo(json: param)

 if (options.bar.isEmpty) {
        print("empty")
  }else{
        print("not emtpy")
       }