protocol Init {
    init(data: [String: Any])
}

func httpGet<T: Init>(completion: (T) -> Void) {
    let data: [String: Any] = ["x": "Awesome"]
    completion(T(data: data))
}

struct Model: Init {
    let x: String
    init(data: [String: Any]) {
        x = data["x"]! as! String
    }
}

httpGet { (model: Model) in

}