# Signature Upload

After a transaction where a signature was collected, call `uploadSignature()` to attach the signature image to the transaction record.


```kotlin
fun uploadSignature(
    pngEncodedBase64: String,
    traceId: String,
)
```

| Parameter | Type | Description |
|  --- | --- | --- |
| `pngEncodedBase64` | `String` | The buyer's signature as a base64-encoded PNG. |
| `traceId` | `String` | The trace ID from the `TransactionResult` returned in `onSuccess`. |


## Usage

Call `uploadSignature()` inside the `onSuccess` callback of `startTransaction()` when `promptForSignature` is not `Never`.