Lifecycle
When Initialize, SetPayload, Enter, Exit and Dispose run.
StateFlow calls a fixed set of methods on every StateFlowComponent in a state, always in the same order. Knowing which ones run before a transition plays, and which wait for it to finish, tells you where each piece of set-up belongs.
The methods
| Method | Runs | Use it to |
|---|---|---|
Initialize() | Once, right after the state is spawned | Cache components, hook up buttons, subscribe to services |
SetPayload(T) | After Initialize, only if the transition carried a payload of a type the state accepts | Store and display the payload |
LateInitialize() | After the payload is set | Set-up that needs both the UI and the payload |
Enter() | When the state becomes the active one, after the transition into it | Start animations and timers, refresh values that may have changed |
TransitionFinished() | Right after Enter, once the transition has completed | Work that should wait until nothing is moving |
Exit() | When another state becomes active: this one is being left, or a higher layer opened on top | Pause what Enter started |
Dispose() | Just before the state is destroyed | Release what Initialize acquired |
The order, case by case
These logs come from the 05 Lifecycle and Observer sample, which logs every call:
Moving to another screen (with a payload)
Observer Alpha → Beta (Hello from Alpha)
AlphaScreen.Exit
AlphaScreen.Dispose
BetaScreen.Initialize
BetaScreen.SetPayload("Hello from Alpha")
BetaScreen.LateInitialize
transition starts
transition ends
BetaScreen.Enter
BetaScreen.TransitionFinishedAlpha is exited and disposed as soon as the transition starts, but it stays on screen until the transition ends, so it can still be animated out. It is destroyed after that.
Opening a popup on top
Observer Alpha → Gamma
AlphaScreen.Exit
GammaPopup.Initialize
GammaPopup.LateInitialize
transition starts
transition ends
GammaPopup.Enter
GammaPopup.TransitionFinishedAlpha gets Exit but not Dispose: it is still open underneath.
Closing the popup
Observer Gamma → Alpha
GammaPopup.Exit
GammaPopup.Dispose
AlphaScreen.Enter
AlphaScreen.TransitionFinishedAlpha is not initialized again. It gets Enter, so refresh anything that the popup might have changed (a balance, a settings value) in Enter, not in Initialize.
The entry state
The entry state runs Initialize, LateInitialize, Enter and TransitionFinished in a row as soon as it has loaded. With Resources loading that happens during the StateFlow Manager's Awake. There is nothing to transition from.
Leaving from Initialize
Enter and Exit always alternate, and a state never gets Exit before it has entered. If a state opens a popup from its own Initialize or LateInitialize, it doesn't enter until that popup closes. If it is replaced that early, it never enters at all, and goes straight to Dispose.
Import Feature Samples from the Package Manager and open 05 Lifecycle and Observer/05 Lifecycle and Observer.unity. About the samples
Child components
Every StateFlowComponent in the state's hierarchy receives the lifecycle calls, root first. Content you spawn at runtime with StateFlowSpawner gets its own lifecycle; see Spawned content.
Exceptions
An exception thrown from any lifecycle method except Initialize is logged, and the remaining components still receive their call, so one broken component can't stall the flow. Keep Initialize free of code that can throw.