所以我在这里创建了一个子组件（名为hello）。在子组件中，你可以找到你的代码。应用程序组件有一个按钮，可以显示/隐藏子组件。所以你可以看到ngOnInit和ngOnDestroy的控制台日志。
Here是更新的Stackblitz链接。

Hello组件（子组件）

export class HelloComponent implements OnInit, OnDestroy {
  selectedPlayer: string;
  playersubscription: Subscription;

  constructor(private playerService: PlayerService) {}

  ngOnInit() {
    console.log('ngOnInit');
    this.playersubscription = this.playerService
      .getSelectedPlayer()
      .subscribe((player) => {
        this.selectedPlayer = player;
        // this.playersubscription.unsubscribe(); If I unsubscribe it here , the functionality breaks
      });
  }

  ngOnDestroy() {
    this.playersubscription.unsubscribe();
    console.log('ngOnDestroy');
  }

  players = [
    {
      name: 'Sachin',
      team: 'MI',
    },
    {
      name: 'Dhoni',
      team: 'CSK',
    },
    {
      name: 'Kohli',
      team: 'RCB',
    },
  ];

  selectPlayer(playerName) {
    this.playerService.updateSelectedPlayer(playerName);
  }
}

应用程序组件

export class AppComponent {
  showChild: boolean = true;

  constructor() {}
  onShowHideClick() {
    this.showChild = !this.showChild;
  }
}

..... and HTML part

<h1>APP COMPONENT</h1>
<button (click)="onShowHideClick()">SHOW / HIDE children</button>
<hr />
<hello *ngIf="showChild"></hello>

做你想要的，如果你明白所有你可以选择我的职位作为答案。
你好弗洛里安