LifecycleObserver constructor
LifecycleObserver()
Avoids calling this constructor in build
method.
Call dispose when it will never be used, e.g. call it in State#dispose.
避免在build
方法里调用该构造方法。记得在State#build
里调用dispose销毁实例。
Implementation
LifecycleObserver() {
_cache.add(this);
WidgetsBinding.instance.addObserver(this);
}