---
title: Callback / Listener interfaces
canonical: https://developer.unico.io/developers/sdks-and-tools/flutter/api-reference/callback-listener-interfaces
locale: en
generated_by: markdown-export
---

- [/](/)
- [SDKs and Tools](/developers/sdks-and-tools/overview)
- [Flutter SDK](/developers/sdks-and-tools/flutter/requirements)
- API Reference
- Callback / Listener interfaces

# Callback / Listener interfaces

UnicoListener (lifecycle)
| Method | Trigger |
| --- | --- |
| `onErrorUnico(UnicoError error)` | Implementation error during SDK operation |
| `onUserClosedCameraManually()` | User closed the camera manually |
| `onSystemClosedCameraTimeoutSession()` | Session expired due to timeout (default: 45 s) |
| `onSystemChangedTypeCameraTimeoutFaceInference()` | No face detected for 13 s — capture switches to manual |

UnicoSelfie (selfie callbacks)
| Method | Trigger |
| --- | --- |
| `onSuccessSelfie(ResultCamera result)` | Selfie capture succeeded |
| `onErrorSelfie(UnicoError error)` | Selfie capture failed |

UnicoSdks (User Journey callback)
| Method | Trigger |
| --- | --- |
| `onSuccess(SuccessResult result)` | Journey flow completed — returns a `processId` (User Journeys only) |
| `onErrorSelfie(UnicoError error)` | Selfie capture failed |

UnicoDocument (document callbacks)
| Method | Trigger |
| --- | --- |
| `onSuccessDocument(ResultCamera result)` | Document capture succeeded |
| `onErrorDocument(UnicoError error)` | Document capture failed |

Last updated on **Oct 22, 2026**