addSubview时隐藏Superview

Question

import { Injectable } from '@angular/core';

@Injectable()
export class ApiService {

client: Client;

  constructor(
    private soap: NgxSoapService
  ) {
    this.soap.createClient('assets/wsdl/auth/auth.wsdl').subscribe(client => this.client = client);
  }
}

我正在尝试创建自定义的navigationItem.titleView，但是当我添加新的subView时，我的superView被隐藏了，并且无法在新控制器上进行传输