Nativescript-Angular 处理后退按钮以更改可见性

Question

我正在尝试更改后退按钮事件中元素的可见性。

 <ActionItem icon="~/images/menu_3_dots.png"  ios.position="right" android.position="right"   *ngIf="isActionItemVisible"></ActionItem>

 constructor(private router: Router, private page: Page) {        
         application.android.on(application.AndroidApplication.activityBackPressedEvent, (args: any) => {           
                        args.cancel = true;
                        console.log("Is backbutton pressed !");
                        this.isActionItemVisible= false;
        });          
}         

变量变为假，但元素没有隐藏。

Answer 1

您有时需要告诉 Angular 执行检测周期以应用更改：

constructor(private router: Router, private page: Page, private cdr: Change
DetectionRef) {        
         application.android.on(application.AndroidApplication.activityBackPressedEvent, (args: any) => {           
                        args.cancel = true;
                        console.log("Is backbutton pressed !");
                        this.isActionItemVisible= false;
                        this.cdr.detectChanges();
        });          
}