如何使用自动完成功能在mat-select的搜索框中设置焦点？

<mat-form-field>
  <mat-select #selectElem [formControl]="myControl" (opened)="setFocus(selectElem)">
    <mat-select-trigger>
      {{ selectedOption }}
    </mat-select-trigger>
    <mat-option *ngFor="let option of options" [value]="option">
      {{ option }}
    </mat-option>
  </mat-select>
</mat-form-field>

import { Component } from '@angular/core';
import { FormControl } from '@angular/forms';

@Component({
  selector: 'app-my-component',
  templateUrl: './my-component.component.html',
  styleUrls: ['./my-component.component.css']
})
export class MyComponent {
  myControl = new FormControl();
  options: string[] = ['Option 1', 'Option 2', 'Option 3'];
  selectedOption: string;

  setFocus(selectElem: any) {
    setTimeout(() => {
      selectElem.focus();
    }, 0);
  }
}