title: ngOnChanges is calling up multiple times
body: <p>I have generated multiple ion-slides using ngFor, and inserted a component there. It is calling ngOnChanges multiple time. I want it should call only once, so that I can call my api.</p>
  
  <p>I have tried using multiple angular lifecycle hooks.</p>
  
  <p>This is how I created my slides, menu has 19 elements</p>
  
  <pre><code>&lt;ion-slides #slides [options]="slideOpts" (ionSlideDidChange)="slideChanged($event)"&gt;
  &lt;ion-slide *ngFor="let i of menu; let j = index"&gt;
    &lt;h1&gt;{{ i.name }}&lt;/h1&gt;
    &lt;app-homenews [categoryId]="currentCategoryId" &gt;&lt;/app-homenews&gt;
  &lt;/ion-slide&gt;
  &lt;/ion-slides&gt;
  </code></pre>
  
  <p>This is how we are making change detection</p>
  
  <pre><code>@Input() categoryId: number;
  
  ngOnChanges(changes: SimpleChanges) {
     let chg = changes['categoryId'];
     console.log(chg.currentValue);
  } 
  </code></pre>
  
  <p>I want it to be called only once, it is calling 19 times now.</p>
  
  <p>Can I use rxjs here ?</p>