fetch(SERVER_SIGNUP_URL + '?username=' + this.state.username + '&password=' + this.state.password)
              .then((response) => response.json())
              .then((responseData) => {
                var id = responseData.id;
                if (id === -1) {
                  this.hideProgressBar();
                  showMessage("Something is bad", "This username is already taken");
                }
                else {
                  this.props.navigator.push({
                    name: 'contacts',
                    password: this.state.password,
                    id: id,
                    username: this.state.username
                  });
                }
              })
        .done();