Ionic2 ng-class on ion-row scss

Ionic Framework ionic-v3
6

Hi,
I am new to ionic. I am using ionic 2. I stuck in using ng class property in typescript file.

Example:
HTML file

<span [ngClass]="displayText">toggled with ngClass</span> <button (click)="toggle()">Toggle</button>

TS file

toggle() {
this.displayText = ‘show-class’;
}

But i am getting error “property does’t exist in typescript class”. How do i access the ngClass property in ionic 2.

Please take me out from this issue.