Ionic 2 Angular 2 - 无法从方法访问NavController

2 回答

• 2

  你需要使用这样的箭头函数：

  navigateIfUserIsLogdIn(){
      this.authState = this.afAuth.authState;
      this.user = this.afAuth.auth.currentUser;
  
      this.afAuth.auth.onAuthStateChanged((user) => {
        if (user) {
          // User is signed in.
          this.navCtrl.setRoot(HomePage);
        } else {
          // No user is signed in.
        }
      });
  }
  

  请注意，现在我们这样做

  this.afAuth.auth.onAuthStateChanged((user) => {...});

  代替

  this.afAuth.auth.onAuthStateChanged(function(user) {

  通过使用箭头函数， the this property is not overwritten and still references the component instance （否则， this 关键字指向内部函数，并且未在其中定义 navCtrl ） .

  回复于 2024-05-03T02:21:44+08:00
• -2

  试着这样做

  constructor(public navCtrl: NavController, public menu: MenuController, public afAuth: AngularFireAuth, public db: AngularFireDatabase, private platform  : Platform) {
      this.navigateIfUserIsLogdIn();
    }
  
    navigateIfUserIsLogdIn(){
          this.authState = this.afAuth.authState;
          this.user = this.afAuth.auth.currentUser;
          var that= this;
          this.afAuth.auth.onAuthStateChanged(function(user) {
            if (user) {
              // User is signed in.
              that.navCtrl.setRoot(HomePage);
            } else {
              // No user is signed in.
            }
          });
    }
  

  回复于 2024-05-03T02:21:44+08:00