ion-select customize interface code example
Example 1: ion-select placeholder
<ion-select placeholder="Select One">
<ion-select-option value="f">Female</ion-select-option>
<ion-select-option value="m">Male</ion-select-option>
</ion-select>
Example 2: ion-select cancel text
<ion-select cancel-text="Cancelar">
<ion-select-option *ngFor="let country of countries" value="{{ country.name }}">
{{ country.name }}
</ion-select-option>
</ion-select>