harmony 鸿蒙PageAbility Lifecycle

2023-02-03
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PageAbility Lifecycle

The PageAbility lifecycle defines all states of a PageAbility, such as INACTIVE, ACTIVE, and BACKGROUND. The figure below shows the lifecycle state transition.

Figure 1 PageAbility lifecycle

page-ability-lifecycle

Table 1 PageAbility lifecycle states

State	Description
UNINITIALIZED	The PageAbility is not initialized. This is a temporary state, from which a PageAbility changes directly to the INITIAL state upon its creation.
INITIAL	The PageAbility is initialized but not running. The PageAbility enters the INACTIVE state after it is started.
INACTIVE	The PageAbility is visible but does not gain focus.
ACTIVE	The PageAbility runs in the foreground and has focus.
BACKGROUND	The PageAbility runs in the background. After being re-activated, the PageAbility enters the ACTIVE state. After being destroyed, it enters the INITIAL state.

You can override the lifecycle callbacks (as described in the table below) in app.js or app.ets.

Table 2 PageAbility lifecycle callbacks

API	Description
onCreate()	Called when the ability is created for the first time. You can initialize the application in this callback.
onDestroy()	Called when the ability is destroyed. In this callback, you can make preparations for application exit, such as recycling resources and clearing the cache.
onActive()	Called when the ability is switched to the foreground and gains focus.
onInactive()	Called when the ability loses focus. An ability loses focus when it is about to enter the background state.
onShow()	Called when the ability is switched from the background to the foreground. In this case, the ability is visible to users.
onHide()	Called when the ability is switched from the foreground to the background. In this case, the ability is invisible to users.

The following figure shows the relationship between lifecycle callbacks and lifecycle states of the PageAbility.

Figure 2 Relationship between lifecycle callbacks and lifecycle states

fa-pageAbility-lifecycle

NOTE

The PageAbility lifecycle callbacks are synchronous.

The app.js file provides only the onCreate and onDestroy callbacks, and the app.ets file provides the full lifecycle callbacks.