目前,我正在使用这个:
class AutoClearedValue<T : Any>(val fragment: Fragment) : ReadWriteProperty<Fragment, T> {
private var _value: T? = null
init {
fragment.lifecycle.addObserver(object: DefaultLifecycleObserver {
override fun onCreate(owner: LifecycleOwner) {
fragment.viewLifecycleOwnerLiveData.observe(fragment) { viewLifecycleOwner ->
viewLifecycleOwner?.lifecycle?.addObserver(object: DefaultLifecycleObserver {
override fun onDestroy(owner: LifecycleOwner) {
_value = null
}
})
}
}
})
}
override fun getValue(thisRef: Fragment, property: KProperty<*>): T {
return _value ?: throw IllegalStateException(
"should never call auto-cleared-value get when it might not be available"
)
}
override fun setValue(thisRef: Fragment, property: KProperty<*>, value: T) {
_value = value
}
}
/**
* Creates an [AutoClearedValue] associated with this fragment.
*/
fun <T : Any> Fragment.autoCleared() = AutoClearedValue<T>(this)
但在我看来,既然我们需要在DestroyView()中使用_binding = null
初始化部分应为:
override fun onDestroyView(owner: LifecycleOwner) {
super.onDestroyView(owner)
_value = null
}
但在我的课堂上,它只是做:
override fun onDestroy(owner: LifecycleOwner) {
_value = null
}
但是onDestroyView在DefaultLifecycleObserver
中不存在。我如何才能做到这一点?
1条答案
按热度按时间3xiyfsfu1#
Fragment.viewLifecycleOwner.lifecycle.addObserver(…)
,则DefaultLifecycleObserver.onDestory(…)
将与Fragment.onDestoryView(…)
同时被调用。Fragment.lifecycle.addObserver(…)
,则DefaultLifecycleObserver.onDestory(…)
将与Fragment.onDestory(…)
同时被调用。这里有一个例子。