LGUILifeCycleBehaviour

Since LGUI use a workflow like Unity does, it is recommanded to use LGUILifeCycleBehaviour as base ActorComponent class for most case, espacially in LGUIPrefab.

When create a Blueprint, typein "LGUILifeCycle" then two class showup, one is LGUILifeCycleBehaviour and the other is LGUILifeCycleUIBehaviour:
Normally just use LGUILifeCycleBehaviour class, it can fit in most use case. LGUILifeCycleUIBehaviour contains some function/ event just for UI elements.

LGUI LifeCycle Behaviour

The life cycle functions of LGUILifeCycleBehaviour are managed uniformly by LGUIManagerActor, and the execution sequence is as follows:
Awake -> OnEnable -> Start -> Update -> OnDisable -> OnDestroy
Awake: LGUILifeCycleBehaviour is executed once when it is loaded into the scene and the IsUIActive of UIItem is true. If LGUILifeCycleBehaviour is created from Prefab, then initialization work needs to be placed in Awake (not BeginPlay), because Awake will execute after all prefab deserialization work is completed.
OnEnable: Execute when GetIsActiveAndEnable of LGUILifeCycleBehaviour changes from false to true.
Start: Execute Start before the first Update is executed.
Update: When GetIsActiveAndEnable is true, it will be executed once every frame.
OnDisable: Execute when GetIsActiveAndEnable of LGUILifeCycleBehaviour changes from true to false, or execute once before OnDestroy and OnEnable has been executed.
OnDestroy: Execute once when LGUILifeCycleBehaviour is destroyed (EndPlay) and Awake has been executed.
Awake/Start/OnDestroy can be executed only once in the whole life cycle, and OnEnable/OnDisalbe/Update may be executed multiple times.
GetIsActiveAndEnable: Returns true when IsUIActive of UIItem is true and enable of LGUILifeCycleBehaviour is true.

Execute order with the UnrealEngine's built-in life cycle function: BeginPlay -> Awake ... OnDestroy -> EndPlay, the Tick function has nothing to do with the Update function.
Awake execute order in prefab: Higher in hierarchy will execute earlier, so scripts on root actor will execute the first, and scripts on lowest actor will execute the last.

Other functions

GetRootSceneComponent: Shotcut and cache for GetOwner->GetRootComponent.

LGUI LifeCycle UI Behaviour

OnUIActiveInHierarchy: Called when RootUIComp IsActiveInHierarchy state is changed. OnUIDimensionsChanged: Called when RootUIComp->AnchorData is changed. OnUIChildDimensionsChanged: Called when RootUIComp's attachchildren->AnchorData is changed. OnUIChildAcitveInHierarchy: Called when RootUIComp's attachchildren IsActiveInHierarchy state is changed. OnUIAttachmentChanged: Called when RootUIComp attach to a new parent. OnUIChildAttachmentChanged: Called when RootUIComp's attachchildren is attached to RootUIComp or detached from RootUIComp. OnUIInteractionStateChanged: Called when RootUIComp's interaction state changed (when UICanvasGroup component allow interaction or not). OnUIChildHierarchyIndexChanged: Called when RootUIComp's attachchildren->SetHierarchyIndex() is called, usually used for layout to sort children.

Other functions

GetRootUIComponent: Shotcut and cache for GetOwner->GetRootComponent->ConvertTo UIItem