import { Injectable } from '@angular/core';
import { Http, Headers } from '@angular/http';
import 'rxjs/add/operator/map';

@Injectable()
export class MyClass {
    token_acces: any;
    token_room: any;

    constructor(private http: Http) {
        this.token_acces = null;
        this.token_room = null;
    }

    login(id,pwd){
        let headers = new Headers();
        headers.append('Content-Type', 'application/json');
        this.http.post('/localhost/',
                        JSON.stringify({
                            username: id ,
                            password: pwd
                        }), {headers : headers})
                    .map(res => res.json())
                    .subscribe(data=>{
                        this.token_acces = data;
                    });
    }

    getToken(){
        return this.token_acces;
    }

}

...
export class HomePage {
    id: any;
    pwd: any;

    constructor(public navCtrl: NavController, public myClassService: MyClass) { }

    login(): void{
        this.myClassService.login(this.id, this.pwd);
        this.navCtrl.push(SearchPage, { token : this.myClassService.getToken()});
    }
}

export class SearchPage {
    token: any;

    constructor(public navCtrl: NavController, public myClassService: MyClass) { }
...