How to creat a dynamic text - ionic-framework

Question

I have a list of titles, and I would like these texts to alternate as I switch to ion-select. How do I do this?
I have no idea how to do this, not even what part of the code to show. I made an attempt here but whenever I use the console the value returned is undefined.
My typescrit code:
import { Titulo } from './../Services/services.service';
import { DataService } from './data.service';
import { Component, OnInit, ViewChild} from '#angular/core';
import {IonSlides} from '#ionic/angular';
import { ActivatedRoute } from '#angular/router';
#Component({
selector: 'app-libertacao',
templateUrl: './libertacao.page.html',
styleUrls: ['./libertacao.page.scss'],
})
export class LibertacaoPage implements OnInit {
#ViewChild(IonSlides) slides: IonSlides;
PAGINA_SELECIONADA: number;
// tslint:disable-next-line: variable-name
index_atual: number;
titulo: Titulo;
constructor(private dataservice: DataService, private activatedRoute: ActivatedRoute ){
}
ngOnInit() {
const id = this.activatedRoute.snapshot.paramMap.get('id');
this.titulo = this.dataservice.getTituloById(parseInt(id, 10));
}
OnChange(event: any)
{
if (event.detail.value === this.PAGINA_SELECIONADA) {
this.slides.slideTo(this.PAGINA_SELECIONADA);
}
else {}
console.log(this.titulo);
}
slideChanged() {
this.slides.getActiveIndex().then((index) => {
this.index_atual = index;
});
}
}