问角度材料步进器在每次点击时动态添加新的步骤项目

EN

<button mat-raised-button (click)="addItem()">
  add item
</button>
 <form [formGroup]="formGroup">
  <mat-horizontal-stepper  formArrayName="form">
    <mat-step [formGroupName]="i" *ngFor="let customerGroup of formGroup.controls.form.controls; let i = index">
      <ng-template matStepLabel>Step {{i + 1}}</ng-template>
      <mat-form-field>
        <input matInput placeholder="Address" formControlName="cont" required>
      </mat-form-field>
    <div>
      <button mat-button matStepperPrevious>Back</button>
      <button mat-button matStepperNext>Next</button>
    </div>
    </mat-step>
  </mat-horizontal-stepper>
</form>

import {Component, OnInit} from '@angular/core';
import {FormBuilder, FormControl,FormGroup, Validators,FormArray} from '@angular/forms';

/**
 * @title Stepper overview
 */
@Component({
  selector: 'stepper-overview-example',
  templateUrl: 'stepper-overview-example.html',
  styleUrls: ['stepper-overview-example.css'],
})
export class StepperOverviewExample implements OnInit {
  isLinear = false;
  formGroup : FormGroup;
  form: FormArray;
  constructor(private _formBuilder: FormBuilder) {    
  }

  ngOnInit() {
    this.formGroup = this._formBuilder.group({
      form : this._formBuilder.array([this.init()])
    }) 
    this.addItem();
  }

  init(){
    return this._formBuilder.group({
      cont :new FormControl('', [Validators.required]),
    })
  }

  addItem(){
    this.form = this.formGroup.get('form') as FormArray;
    this.form.push(this.init());
  }
}