//1
self.sendNetworkOperation(
    params: ["Token":"Bearer aaaaaaaaaa","limit": 100],
    completion: { (res) in
        switch res.0{ //6
            case true:
                //success
                break
            case false:
                //error
                break
            }
    })

func isReachable() -> Bool {
    let reachability = Reachability()! //3

    if reachability.isReachable{ //4
        return true
    }

    return false
}

func sendNetworkOperation(
    params: Dictionary<String,Any>,
    completion: ((Bool,String?)->())){
    //2
    if self.isReachable(){
        //5
        //send operation
        completion(true, nil)
    } else {
        //5
        completion(false, "Error, network is not reachable")
    }
}