ionViewDidEnter() {
    this.loadmap();
  }

  ionViewDidLoad() {
    
  }

ionViewDidLoad  void  Runs when the page has loaded. This event only happens once per page being created. If a page leaves but is cached, then this event will not fire again on a subsequent viewing. The ionViewDidLoad event is good place to put your setup code for the page.
ionViewWillEnter  void  Runs when the page is about to enter and become the active page.
ionViewDidEnter  void  Runs when the page has fully entered and is now the active page. This event will fire, whether it was the first load or a cached page.
ionViewWillLeave  void  Runs when the page is about to leave and no longer be the active page.
ionViewDidLeave  void  Runs when the page has finished leaving and is no longer the active page.
ionViewWillUnload  void  Runs when the page is about to be destroyed and have its elements removed.
ionViewCanEnter  boolean/Promise<void>  Runs before the view can enter. This can be used as a sort of "guard" in authenticated views where you need to check permissions before the view can enter
ionViewCanLeave  boolean/Promise<void>  Runs before the view can leave. This can be used as a sort of "guard" in authenticated views where you need to check permissions before the view can leave