<ion-input type="{{pwshow?'text':'password'}}" placeholder="输入密码"></ion-input>

 <a href="javascript:;" rel="external nofollow" item-end (click)="pwshow=!pwshow" [ngClass]="pwshow?'eyeshow':'eyehide'">
  <ion-icon name="ios-eye-off" color="dark" class="eye-hide"></ion-icon>　　<!--闭眼图标-->
  <ion-icon name="ios-eye" color="dark" class="eye-show"></ion-icon>　　<!--睁眼图标-->
 </a>

.eyehide .eye-hide, .eyeshow .eye-show{
  display: block;
}
.eyehidee .eye-show, .eyeshow .eye-hide{
  display: none;
}