Include filename extension for attachments

Fixes posting attachments on pleroma resulting in them served as
application/octet-stream, even though we're sending the mime type as well

Tusker/Models/CompositionAttachmentData.swift

@@ -48,13 +48,13 @@ enum CompositionAttachmentData {
         }
     }
     
-    func getData(completion: @escaping (Result<(Data, String), Error>) -> Void) {
+    func getData(completion: @escaping (Result<(Data, UTType), Error>) -> Void) {
         switch self {
         case let .image(image):
             // Export as JPEG instead of PNG, otherweise photos straight from the camera are too large
             // for Mastodon in its default configuration (max of 10MB).
             // The quality of 0.8 was chosen completely arbitrarily, it may need to be tuned in the future.
-            completion(.success((image.jpegData(compressionQuality: 0.8)!, "image/jpeg")))
+            completion(.success((image.jpegData(compressionQuality: 0.8)!, .jpeg)))
         case let .asset(asset):
             if asset.mediaType == .image {
                 let options = PHImageRequestOptions()
@@ -68,19 +68,19 @@ enum CompositionAttachmentData {
                         return
                     }
     
-                    let mimeType: String
+                    let utType: UTType
                     if dataUTI == "public.heic" {
                         // neither Mastodon nor Pleroma handles HEIC well, so convert to JPEG
                         let image = CIImage(data: data)!
                         let context = CIContext()
                         let colorSpace = image.colorSpace ?? CGColorSpace(name: CGColorSpace.sRGB)!
                         data = context.jpegRepresentation(of: image, colorSpace: colorSpace, options: [:])!
-                        mimeType = "image/jpeg"
+                        utType = .jpeg
                     } else {
-                        mimeType = UTType(dataUTI)!.preferredMIMEType!
+                        utType = UTType(dataUTI)!
                     }
     
-                    completion(.success((data, mimeType)))
+                    completion(.success((data, utType)))
                 }
             } else if asset.mediaType == .video {
                 let options = PHVideoRequestOptions()
@@ -109,11 +109,11 @@ enum CompositionAttachmentData {
             
         case let .drawing(drawing):
             let image = drawing.imageInLightMode(from: drawing.bounds, scale: 1)
-            completion(.success((image.pngData()!, "image/png")))
+            completion(.success((image.pngData()!, .png)))
         }
     }
     
-    private static func exportVideoData(session: AVAssetExportSession, completion: @escaping (Result<(Data, String), Error>) -> Void) {
+    private static func exportVideoData(session: AVAssetExportSession, completion: @escaping (Result<(Data, UTType), Error>) -> Void) {
         session.outputFileType = .mp4
         session.outputURL = FileManager.default.temporaryDirectory.appendingPathComponent("exported_video_\(UUID())").appendingPathExtension("mp4")
         session.exportAsynchronously {
@@ -123,7 +123,7 @@ enum CompositionAttachmentData {
             }
             do {
                 let data = try Data(contentsOf: session.outputURL!)
-                completion(.success((data, "video/mp4")))
+                completion(.success((data, .mpeg4Movie)))
             } catch {
                 completion(.failure(.videoExport(error)))
             }

Tusker/Services/PostService.swift

@@ -8,6 +8,7 @@
 
 import Foundation
 import Pachyderm
+import UniformTypeIdentifiers
 
 class PostService: ObservableObject {
     private let mastodonController: MastodonController
@@ -66,15 +67,15 @@ class PostService: ObservableObject {
         attachments.reserveCapacity(draft.attachments.count)
         for (index, attachment) in draft.attachments.enumerated() {
             let data: Data
-            let mimeType: String
+            let utType: UTType
             do {
-                (data, mimeType) = try await getData(for: attachment)
+                (data, utType) = try await getData(for: attachment)
                 currentStep += 1
             } catch let error as CompositionAttachmentData.Error {
                 throw Error.attachmentData(index: index, cause: error)
             }
             do {
-                let uploaded = try await uploadAttachment(data: data, mimeType: mimeType, description: attachment.attachmentDescription)
+                let uploaded = try await uploadAttachment(data: data, utType: utType, description: attachment.attachmentDescription)
                 attachments.append(uploaded)
                 currentStep += 1
             } catch let error as Client.Error {
@@ -84,7 +85,7 @@ class PostService: ObservableObject {
         return attachments
     }
     
-    private func getData(for attachment: CompositionAttachment) async throws -> (Data, String) {
+    private func getData(for attachment: CompositionAttachment) async throws -> (Data, UTType) {
         return try await withCheckedThrowingContinuation { continuation in
             attachment.data.getData { result in
                 switch result {
@@ -97,8 +98,8 @@ class PostService: ObservableObject {
         }
     }
     
-    private func uploadAttachment(data: Data, mimeType: String, description: String?) async throws -> Attachment {
+    private func uploadAttachment(data: Data, utType: UTType, description: String?) async throws -> Attachment {
-        let formAttachment = FormAttachment(mimeType: mimeType, data: data, fileName: "file")
+        let formAttachment = FormAttachment(mimeType: utType.preferredMIMEType!, data: data, fileName: "file.\(utType.preferredFilenameExtension!)")
         let req = Client.upload(attachment: formAttachment, description: description)
         return try await mastodonController.run(req).0
     }