MultipartFormData

Constructs multipart/form-data for uploads within an HTTP or HTTPS body. There are currently two ways to encode multipart form data. The first way is to encode the data directly in memory. This is very efficient, but can lead to memory issues if the dataset is too large. The second way is designed for larger datasets and will write all the data to a single file on disk with all the proper boundary segmentation. The second approach MUST be used for larger datasets such as video content, otherwise your app may run out of memory when trying to encode the dataset.

open class MultipartFormData

For more information on multipart/form-data in general, please refer to the RFC-2388 and RFC-2045 specs as well and the w3 form documentation.

• https:​//www.ietf.org/rfc/rfc2388.txt

• https:​//www.ietf.org/rfc/rfc2045.txt

• https:​//www.w3.org/TR/html401/interact/forms.html#h-17.13

Initializers

init(fileManager:​boundary:​)

Creates an instance.

public init(fileManager:​ FileManager = .default, boundary:​ String? = nil)

Parameters

• fileManager:​ FileManager to use for file operations, if needed.
• boundary:​ Boundary String used to separate body parts.

Properties

encodingMemoryThreshold

Default memory threshold used when encoding MultipartFormData, in bytes.

let encodingMemoryThreshold:​ UInt64 = 10_000_000

contentType

The Content-Type header value containing the boundary used to generate the multipart/form-data.

var contentType:​ String = "multipart/form-data; boundary=\(self.boundary)"

contentLength

The content length of all body parts used to generate the multipart/form-data not including the boundaries.

var contentLength:​ UInt64

boundary

The boundary used to separate the body parts in the encoded form data.

let boundary:​ String

Methods

append(_:​withName:​fileName:​mimeType:​)

Creates a body part from the data and appends it to the instance.

public func append(_ data:​ Data, withName name:​ String, fileName:​ String? = nil, mimeType:​ String? = nil)

The body part data will be encoded using the following format:​

• Content-Disposition:​ form-data; name=#{name}; filename=#{filename} (HTTP Header)

• Content-Type:​ #{mimeType} (HTTP Header)

• Encoded file data

• Multipart form boundary

Parameters

• data:​ Data to encoding into the instance.
• name:​ Name to associate with the Data in the Content-Disposition HTTP header.
• fileName:​ Filename to associate with the Data in the Content-Disposition HTTP header.
• mimeType:​ MIME type to associate with the data in the Content-Type HTTP header.

append(_:​withName:​)

Creates a body part from the file and appends it to the instance.

public func append(_ fileURL:​ URL, withName name:​ String)

The body part data will be encoded using the following format:​

• Content-Disposition:​ form-data; name=#{name}; filename=#{generated filename} (HTTP Header)

• Content-Type:​ #{generated mimeType} (HTTP Header)

• Encoded file data

• Multipart form boundary

The filename in the Content-Disposition HTTP header is generated from the last path component of the fileURL. The Content-Type HTTP header MIME type is generated by mapping the fileURL extension to the system associated MIME type.

Parameters

• fileURL:​ URL of the file whose content will be encoded into the instance.
• name:​ Name to associate with the file content in the Content-Disposition HTTP header.

append(_:​withName:​fileName:​mimeType:​)

Creates a body part from the file and appends it to the instance.

public func append(_ fileURL:​ URL, withName name:​ String, fileName:​ String, mimeType:​ String)

The body part data will be encoded using the following format:​

• Content-Disposition:​ form-data; name=#{name}; filename=#{filename} (HTTP Header)

• Content-Type:​ #{mimeType} (HTTP Header)

• Encoded file data

• Multipart form boundary

Parameters

• fileURL:​ URL of the file whose content will be encoded into the instance.
• name:​ Name to associate with the file content in the Content-Disposition HTTP header.
• fileName:​ Filename to associate with the file content in the Content-Disposition HTTP header.
• mimeType:​ MIME type to associate with the file content in the Content-Type HTTP header.

append(_:​withLength:​name:​fileName:​mimeType:​)

Creates a body part from the stream and appends it to the instance.

public func append(_ stream:​ InputStream, withLength length:​ UInt64, name:​ String, fileName:​ String, mimeType:​ String)

The body part data will be encoded using the following format:​

• Content-Disposition:​ form-data; name=#{name}; filename=#{filename} (HTTP Header)

• Content-Type:​ #{mimeType} (HTTP Header)

• Encoded stream data

• Multipart form boundary

Parameters

• stream:​ InputStream to encode into the instance.
• length:​ Length, in bytes, of the stream.
• name:​ Name to associate with the stream content in the Content-Disposition HTTP header.
• fileName:​ Filename to associate with the stream content in the Content-Disposition HTTP header.
• mimeType:​ MIME type to associate with the stream content in the Content-Type HTTP header.

append(_:​withLength:​headers:​)

Creates a body part with the stream, length, and headers and appends it to the instance.

public func append(_ stream:​ InputStream, withLength length:​ UInt64, headers:​ HTTPHeaders)

The body part data will be encoded using the following format:​

• HTTP headers

• Encoded stream data

• Multipart form boundary

Parameters

• stream:​ InputStream to encode into the instance.
• length:​ Length, in bytes, of the stream.
• headers:​ HTTPHeaders for the body part.

encode()

Encodes all appended body parts into a single Data value.

public func encode() throws -> Data

Throws

An AFError if encoding encounters an error.

Returns

The encoded Data, if encoding is successful.

writeEncodedData(to:​)

Writes all appended body parts to the given file URL.

public func writeEncodedData(to fileURL:​ URL) throws

This process is facilitated by reading and writing with input and output streams, respectively. Thus, this approach is very memory efficient and should be used for large body part data.

Parameters

• fileURL:​ File URL to which to write the form data.

Throws

An AFError if encoding encounters an error.