Refactored upload APIs for MultipartFormData to support custom boundaries

Source/Alamofire.swift

@@ -337,6 +337,7 @@ public enum AF {
     /// - Parameters:
     ///   - multipartFormData:       The closure used to append body parts to the `MultipartFormData`.
     ///   - encodingMemoryThreshold: The encoding memory threshold in bytes. `10_000_000` bytes by default.
+    ///   - fileManager:             The `FileManager` instance to use to manage streaming and encoding.
     ///   - url:                     The `URLConvertible` value.
     ///   - method:                  The `HTTPMethod`, `.post` by default.
     ///   - headers:                 The `HTTPHeaders`, `nil` by default.
@@ -345,12 +346,14 @@ public enum AF {
     /// - Returns: The created `UploadRequest`.
     public static func upload(multipartFormData: @escaping (MultipartFormData) -> Void,
                               usingThreshold encodingMemoryThreshold: UInt64 = MultipartUpload.encodingMemoryThreshold,
+                              fileManager: FileManager = .default,
                               to url: URLConvertible,
                               method: HTTPMethod = .post,
                               headers: HTTPHeaders? = nil,
                               interceptor: RequestInterceptor? = nil) -> UploadRequest {
         return Session.default.upload(multipartFormData: multipartFormData,
                                       usingThreshold: encodingMemoryThreshold,
+                                      fileManager: fileManager,
                                       to: url,
                                       method: method,
                                       headers: headers,
@@ -381,7 +384,7 @@ public enum AF {
     ///
     /// - Returns: The `UploadRequest` created.
     @discardableResult
-    public static func upload(multipartFormData: @escaping (MultipartFormData) -> Void,
+    public static func upload(multipartFormData: MultipartFormData,
                               usingThreshold encodingMemoryThreshold: UInt64 = MultipartUpload.encodingMemoryThreshold,
                               with urlRequest: URLRequestConvertible,
                               interceptor: RequestInterceptor? = nil) -> UploadRequest {

Source/MultipartFormData.swift

@@ -100,7 +100,8 @@ open class MultipartFormData {
     /// The boundary used to separate the body parts in the encoded form data.
     public let boundary: String
 
-    private let fileManager: FileManager
+    let fileManager: FileManager
+
     private var bodyParts: [BodyPart]
     private var bodyPartError: AFError?
     private let streamBufferSize: Int

Source/MultipartUpload.swift

@@ -31,7 +31,7 @@ open class MultipartUpload {
     lazy var result = Result { try build() }
 
     let isInBackgroundSession: Bool
-    let multipartBuilder: (MultipartFormData) -> Void
+    let multipartFormData: MultipartFormData
     let encodingMemoryThreshold: UInt64
     let request: URLRequestConvertible
     let fileManager: FileManager
@@ -39,25 +39,21 @@ open class MultipartUpload {
     init(isInBackgroundSession: Bool,
          encodingMemoryThreshold: UInt64 = MultipartUpload.encodingMemoryThreshold,
          request: URLRequestConvertible,
-         fileManager: FileManager = .default,
-         multipartBuilder: @escaping (MultipartFormData) -> Void) {
+         multipartFormData: MultipartFormData) {
         self.isInBackgroundSession = isInBackgroundSession
         self.encodingMemoryThreshold = encodingMemoryThreshold
         self.request = request
-        self.fileManager =  fileManager
-        self.multipartBuilder = multipartBuilder
+        self.fileManager =  multipartFormData.fileManager
+        self.multipartFormData = multipartFormData
     }
 
     func build() throws -> (request: URLRequest, uploadable: UploadRequest.Uploadable) {
-        let formData = MultipartFormData(fileManager: fileManager)
-        multipartBuilder(formData)
-
         var urlRequest = try request.asURLRequest()
-        urlRequest.setValue(formData.contentType, forHTTPHeaderField: "Content-Type")
+        urlRequest.setValue(multipartFormData.contentType, forHTTPHeaderField: "Content-Type")
 
         let uploadable: UploadRequest.Uploadable
-        if formData.contentLength < encodingMemoryThreshold && !isInBackgroundSession {
-            let data = try formData.encode()
+        if multipartFormData.contentLength < encodingMemoryThreshold && !isInBackgroundSession {
+            let data = try multipartFormData.encode()
 
             uploadable = .data(data)
         } else {
@@ -69,7 +65,7 @@ open class MultipartUpload {
             try fileManager.createDirectory(at: directoryURL, withIntermediateDirectories: true, attributes: nil)
 
             do {
-                try formData.writeEncodedData(to: fileURL)
+                try multipartFormData.writeEncodedData(to: fileURL)
             } catch {
                 // Cleanup after attempted write if it fails.
                 try? fileManager.removeItem(at: fileURL)

Source/Session.swift

@@ -326,22 +326,23 @@ open class Session {
                      interceptor: RequestInterceptor? = nil) -> UploadRequest {
         let convertible = ParameterlessRequestConvertible(url: url, method: method, headers: headers)
 
-        return upload(multipartFormData: multipartFormData,
+        let formData = MultipartFormData(fileManager: fileManager)
+        multipartFormData(formData)
+
+        return upload(multipartFormData: formData,
                       usingThreshold: encodingMemoryThreshold,
                       with: convertible,
                       interceptor: interceptor)
     }
 
-    open func upload(multipartFormData: @escaping (MultipartFormData) -> Void,
+    open func upload(multipartFormData: MultipartFormData,
                      usingThreshold encodingMemoryThreshold: UInt64 = MultipartUpload.encodingMemoryThreshold,
-                     fileManager: FileManager = .default,
                      with request: URLRequestConvertible,
                      interceptor: RequestInterceptor? = nil) -> UploadRequest {
         let multipartUpload = MultipartUpload(isInBackgroundSession: (session.configuration.identifier != nil),
                                               encodingMemoryThreshold: encodingMemoryThreshold,
                                               request: request,
-                                              fileManager: fileManager,
-                                              multipartBuilder: multipartFormData)
+                                              multipartFormData: multipartFormData)
 
         return upload(multipartUpload, interceptor: interceptor)
     }