ionic中的生命周期函数

Ionic4 中内置的生命周期函数

ionViewWillEnter —当进入一个页面时触发(如果它从堆栈返回)
ionViewDidEnter —进入后触发
ionViewWillLeave —如果页面将离开触发
ionViewDidLeave — 在页面离开后触发
ionViewWillUnload — 页面卸载的时候会触发，如果无法触发使用 ngOnDestroy

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

Ionic4 可以使用的 Angular 生命周期函数

ngOnChanges 当被绑定的输入属性的值发生变化时调用(父子组件传值的时候会触发
ngOnInit 请求数据一般放在这个里面 (重要*)
ngDoCheck 检测，并在发生 Angular 无法或不愿意自己检测的变化时作出反应
ngAfterContentInit 当把内容投影进组件之后调用
ngAfterContentChecked 每次完成被投影组件内容的变更检测之后调用
ngAfterViewInit 初始化完组件视图及其子视图之后调用(dom 操作放在这个里面)(重 要)
ngAfterViewChecked 每次做完组件视图和子视图的变更检测之后调用
ngOnDestroy 组件销毁后执行 (重要)