---
title: "init(specification:blobMapping:)"
framework: coreml
role: symbol
role_heading: Initializer
path: "coreml/mlmodelasset/init(specification:blobmapping:)"
---

# init(specification:blobMapping:)

Construct a model asset from an ML Program specification by replacing blob file references with corresponding in-memory blobs.

## Declaration

```swift
convenience init(specification specificationData: Data, blobMapping: [URL : Data]) throws
```

## Parameters

- `blobMapping`: A dictionary with blob URL as the key and blob data as the value.

## Discussion

Discussion An ML Program may use BlobFileValue syntax, which stores the blob data in external files and refers them by URL. This factory method enables in-memory workflow for such models by using the specified in-memory blob data in place of the external files. The format of in-memory blobs must be the same as the external files. The dictionary must contain all the reference URLs used in the specification.

## See Also

### Creating a model asset

- [init(specification:)](coreml/mlmodelasset/init(specification:).md)
- [init(url:)](coreml/mlmodelasset/init(url:)-43988.md)