离子3: Back Button硬件事件处理程序无法确定覆盖视图

Question

我有一个离子3应用程序，我修改了硬件后退按钮的功能。它可以在页面上工作，但它不能确定是否存在覆盖视图(如modals和警报对话框)。

这里是我的代码

    this.platform.registerBackButtonAction(() => { 
      let nav = app._appRoot._getActivePortal() || app.getActiveNav();
      let activeView = nav.getActive().instance;

      if (activeView != null) {
        if (nav.canGoBack()) {
            if (activeView instanceof MultiRegistrationOne || activeView instanceof MultiRegistrationTwo || activeView instanceof MultiRegistrationThree) {
                // do something
            } else {
               nav.pop();
            }
        } else if (activeView.isOverlay) {
          activeView.dismiss();
        } else {
          let alert = this.alertCtrl.create({
            title: 'Ionic App',
            message: 'Do you want to close the app?',
            buttons: [{
              text: 'Cancel',
              role: 'cancel',
              handler: () => {
                console.log('Application exit prevented!');
              }
            },
            {
              text: 'Close',
              handler: () => {
                this.platform.exitApp();
              }
            }]
          });
          alert.present();
        }
      }
    });

我希望有人能帮我这个忙。提前谢谢你

Answer 1

我用MD解决了这个问题。利雅斯的回答：Solution

Answer 2

声明一个变量:viewController:ViewController然后在您的页面或app.components.ts中，修改您的后退按钮句柄，使其类似于

this.platform.registerBackButtonAction(() => {
  try{
    this.viewController.dismiss()

  }
  catch(e){
    console.log("error");
  }

});