ionic3中 input怎么获取焦点

Question

ionic3中 input怎么获取焦点

<input type="search" placeholder="请输入关键字，以便查询相关信息" [(ngModel)]="myInput" class="search" (ngModelChange)="onInput()">

import { Component,ElementRef } from '@angular/core';

export class AddBankcardPage{

 private ab;//申明

 constructor( public ele:ElementRef){ 

 this.ab=this.ele.nativeElement.querySelector('.search');

 console.log("------------"+this.ab); //获取不到dom

 this.ab.focus();

}

}