New Error Handling

Source/MultipartFormData.swift

@@ -101,7 +101,7 @@ open class MultipartFormData {
     public let boundary: String
 
     private var bodyParts: [BodyPart]
-    private var bodyPartError: NSError?
+    private var bodyPartError: Error?
     private let streamBufferSize: Int
 
     // MARK: - Lifecycle
@@ -206,8 +206,7 @@ open class MultipartFormData {
             let mime = mimeType(forPathExtension: pathExtension)
             append(fileURL, withName: name, fileName: fileName, mimeType: mime)
         } else {
-            let failureReason = "Failed to extract the fileName of the provided URL: \(fileURL)"
-            setBodyPartError(withCode: NSURLErrorBadURL, failureReason: failureReason)
+            setBodyPartError(withReason: .failedToExtractFilename(for: fileURL))
         }
     }
 
@@ -232,19 +231,22 @@ open class MultipartFormData {
         //============================================================
 
         guard fileURL.isFileURL else {
-            let failureReason = "The file URL does not point to a file URL: \(fileURL)"
-            setBodyPartError(withCode: NSURLErrorBadURL, failureReason: failureReason)
+            setBodyPartError(withReason: .notAFile(at: fileURL))
             return
         }
 
         //============================================================
         //              Check 2 - is file URL reachable?
         //============================================================
-
-        let isReachable = (fileURL as NSURL).checkPromisedItemIsReachableAndReturnError(nil)
-
-        guard isReachable else {
-            setBodyPartError(withCode: NSURLErrorBadURL, failureReason: "The file URL is not reachable: \(fileURL)")
+
+        do {
+            let isReachable = try fileURL.checkPromisedItemIsReachable()
+            guard isReachable else {
+                setBodyPartError(withReason: .fileNotReachable(at: fileURL))
+                return
+            }
+        } catch {
+            bodyPartError = error
             return
         }
 
@@ -257,8 +259,7 @@ open class MultipartFormData {
 
         guard FileManager.default.fileExists(atPath: path, isDirectory: &isDirectory) && !isDirectory.boolValue else
         {
-            let failureReason = "The file URL is a directory, not a file: \(fileURL)"
-            setBodyPartError(withCode: NSURLErrorBadURL, failureReason: failureReason)
+            setBodyPartError(withReason: .isDirectory(at: fileURL))
             return
         }
 
@@ -278,8 +279,7 @@ open class MultipartFormData {
         }
 
         guard let length = bodyContentLength else {
-            let failureReason = "Could not fetch attributes from the file URL: \(fileURL)"
-            setBodyPartError(withCode: NSURLErrorBadURL, failureReason: failureReason)
+            setBodyPartError(withReason: .failedToFetchAttributes(from: fileURL))
             return
         }
 
@@ -288,8 +288,7 @@ open class MultipartFormData {
         //============================================================
 
         guard let stream = InputStream(url: fileURL) else {
-            let failureReason = "Failed to create an input stream from the file URL: \(fileURL)"
-            setBodyPartError(withCode: NSURLErrorCannotOpenFile, failureReason: failureReason)
+            setBodyPartError(withReason: .failedToCreateInputStream(from: fileURL))
             return
         }
 
@@ -339,13 +338,13 @@ open class MultipartFormData {
 
     // MARK: - Data Encoding
 
-    /// Encodes all the appended body parts into a single `NSData` object.
+    /// Encodes all the appended body parts into a single `Data` value.
     ///
     /// It is important to note that this method will load all the appended body parts into memory all at the same
     /// time. This method should only be used when the encoded data will have a small memory footprint. For large data
     /// cases, please use the `writeEncodedDataToDisk(fileURL:completionHandler:)` method.
     ///
-    /// - throws: An `NSError` if encoding encounters an error.
+    /// - throws: An `AFError` if encoding encounters an error.
     ///
     /// - returns: The encoded `Data` if encoding is successful.
     public func encode() throws -> Data {
@@ -373,18 +372,18 @@ open class MultipartFormData {
     ///
     /// - parameter fileURL: The file URL to write the multipart form data into.
     ///
-    /// - throws: An `NSError` if encoding encounters an error.
+    /// - throws: An `AFError` if encoding encounters an error.
     public func writeEncodedDataToDisk(_ fileURL: URL) throws {
         if let bodyPartError = bodyPartError {
             throw bodyPartError
         }
 
         if FileManager.default.fileExists(atPath: fileURL.path) {
             let failureReason = "A file already exists at the given file URL: \(fileURL)"
-            throw NSError(domain: NSURLErrorDomain, code: NSURLErrorBadURL, failureReason: failureReason)
+            throw AFError.outputStreamWriteFailed(reason: .fileAlreadyExists(at: fileURL))
         } else if !fileURL.isFileURL {
             let failureReason = "The URL does not point to a valid file: \(fileURL)"
-            throw NSError(domain: NSURLErrorDomain, code: NSURLErrorBadURL, failureReason: failureReason)
+            throw AFError.outputStreamWriteFailed(reason: .invalidFile(at: fileURL))
         }
 
         let outputStream: OutputStream
@@ -393,19 +392,18 @@ open class MultipartFormData {
             outputStream = possibleOutputStream
         } else {
             let failureReason = "Failed to create an output stream with the given URL: \(fileURL)"
-            throw NSError(domain: NSURLErrorDomain, code: NSURLErrorCannotOpenFile, failureReason: failureReason)
+            throw AFError.outputStreamWriteFailed(reason: .failedToCreateStream(at: fileURL))
         }
 
         outputStream.open()
+        defer { outputStream.close() }
 
         self.bodyParts.first?.hasInitialBoundary = true
         self.bodyParts.last?.hasFinalBoundary = true
 
         for bodyPart in self.bodyParts {
             try write(bodyPart, to: outputStream)
         }
-
-        outputStream.close()
     }
 
     // MARK: - Private - Body Part Encoding
@@ -459,8 +457,7 @@ open class MultipartFormData {
             if bytesRead > 0 {
                 encoded.append(buffer, count: bytesRead)
             } else if bytesRead < 0 {
-                let failureReason = "Failed to read from input stream: \(inputStream)"
-                error = NSError(domain: NSURLErrorDomain, code: .inputStreamReadFailed, failureReason: failureReason)
+                error = AFError.inputStreamReadFailed(inputStream: inputStream)
                 break
             } else {
                 break
@@ -514,8 +511,7 @@ open class MultipartFormData {
 
                 try write(&buffer, to: outputStream)
             } else if bytesRead < 0 {
-                let failureReason = "Failed to read from input stream: \(inputStream)"
-                throw NSError(domain: NSURLErrorDomain, code: .inputStreamReadFailed, failureReason: failureReason)
+                throw AFError.inputStreamReadFailed(inputStream: inputStream)
             } else {
                 break
             }
@@ -551,8 +547,7 @@ open class MultipartFormData {
                 }
 
                 if bytesWritten < 0 {
-                    let failureReason = "Failed to write to output stream: \(outputStream)"
-                    throw NSError(domain: NSURLErrorDomain, code: .outputStreamWriteFailed, failureReason: failureReason)
+                    throw AFError.outputStreamWriteFailed(reason: .writeFailed(to: outputStream))
                 }
 
                 bytesToWrite -= bytesWritten
@@ -607,8 +602,8 @@ open class MultipartFormData {
 
     // MARK: - Private - Errors
 
-    private func setBodyPartError(withCode code: Int, failureReason: String) {
+    private func setBodyPartError(withReason reason: AFError.MultipartEncodingFailureReason) {
         guard bodyPartError == nil else { return }
-        bodyPartError = NSError(domain: NSURLErrorDomain, code: code, failureReason: failureReason)
+        bodyPartError = AFError.multipartEncodingFailed(reason: reason)
     }
 }

Source/ParameterEncoding.swift

@@ -70,7 +70,7 @@ public enum ParameterEncoding {
     case urlEncodedInURL
     case json
     case propertyList(PropertyListSerialization.PropertyListFormat, PropertyListSerialization.WriteOptions)
-    case custom((URLRequestConvertible, [String: Any]?) -> (URLRequest, NSError?))
+    case custom((URLRequestConvertible, [String: Any]?) -> (URLRequest, Error?))
 
     /// Creates a URL request by encoding parameters and applying them onto an existing request.
     ///
@@ -82,13 +82,13 @@ public enum ParameterEncoding {
     public func encode(
         _ urlRequest: URLRequestConvertible,
         parameters: [String: Any]?)
-        -> (URLRequest, NSError?)
+        -> (URLRequest, Error?)
     {
         var urlRequest = urlRequest.urlRequest
 
         guard let parameters = parameters else { return (urlRequest, nil) }
 
-        var encodingError: NSError? = nil
+        var encodingError: Error? = nil
 
         switch self {
         case .url, .urlEncodedInURL:
@@ -143,16 +143,15 @@ public enum ParameterEncoding {
             }
         case .json:
             do {
-                let options = JSONSerialization.WritingOptions()
-                let data = try JSONSerialization.data(withJSONObject: parameters, options: options)
+                let data = try JSONSerialization.data(withJSONObject: parameters, options: [])
 
                 if urlRequest.value(forHTTPHeaderField: "Content-Type") == nil {
                     urlRequest.setValue("application/json", forHTTPHeaderField: "Content-Type")
                 }
 
                 urlRequest.httpBody = data
             } catch {
-                encodingError = error as NSError
+                encodingError = error
             }
         case .propertyList(let format, let options):
             do {
@@ -168,7 +167,7 @@ public enum ParameterEncoding {
 
                 urlRequest.httpBody = data
             } catch {
-                encodingError = error as NSError
+                encodingError = error
             }
         case .custom(let closure):
             (urlRequest, encodingError) = closure(urlRequest, parameters)

Source/Response.swift

@@ -25,7 +25,7 @@
 import Foundation
 
 /// Used to store all response data returned from a completed `Request`.
-public struct Response<ValueType, ErrorType: Error> {
+public struct Response<Value> {
     /// The URL request sent to the server.
     public let request: URLRequest?
 
@@ -36,7 +36,7 @@ public struct Response<ValueType, ErrorType: Error> {
     public let data: Data?
 
     /// The result of response serialization.
-    public let result: Result<ValueType, ErrorType>
+    public let result: Result<Value>
 
     /// The timeline of the complete lifecycle of the `Request`.
     public let timeline: Timeline
@@ -55,7 +55,7 @@ public struct Response<ValueType, ErrorType: Error> {
         request: URLRequest?,
         response: HTTPURLResponse?,
         data: Data?,
-        result: Result<ValueType, ErrorType>,
+        result: Result<Value>,
         timeline: Timeline = Timeline())
     {
         self.request = request