[api-upload-refactor] Set deployment target to iOS 15, simplify upload

- Package.swift: .iOS(.v13) -> .iOS(.v15), .watchOS(.v6) -> .v8
  (README already stated iOS 15; watchOS 8 needed for URLSession.upload(for:fromFile:))
- drop the iOS-13 uploadTask continuation bridge; both upload overloads now
  share one runUpload using session.upload(for:fromFile:delegate:)
- remove now-redundant @available(iOS 15) from the progress overload and test
- Documentation/API.md: drop iOS-version caveats

Documentation/API.md

@@ -30,7 +30,7 @@ let user: User = try await API.shared.request(
 | Large file upload loads the whole file into a `Data` | `form.file(_:url:)` streams from disk in 64 KB chunks |
 | Retry logic copy-pasted, often unbounded | `persistConnection: true`, bounded by `API.maxPersistRetries` |
 | Client-certificate (mTLS) needs a custom `URLSessionDelegate` per project | `setupCertification(certData:password:)` |
-| Progress reporting needs a delegate + KVO wiring | `upload(..., onProgress:)` (iOS 15+) |
+| Progress reporting needs a delegate + KVO wiring | `upload(..., onProgress:)` |
 | `@MainActor` hops or manual `DispatchQueue` juggling | `actor`-isolated, `Sendable`-checked, runs off the main thread |
 | Response types must be `Codable` even when only decoding | `T: Decodable & Sendable` |
 
@@ -177,9 +177,9 @@ let result: UploadResult = try await API.shared.upload(
 ```
 
 The body is serialised to a temp file and always removed afterwards, on success
-and on throw. Works on iOS 13+.
+and on throw.
 
-### With progress (iOS 15+)
+### With progress
 
 ```swift
 let result: UploadResult = try await API.shared.upload(

Package.resolved

@@ -1,5 +1,5 @@
 {
-  "originHash" : "50e672f8971a68675dcb3ca27b4bd4832c7e96f2216ae062f002554d445c6714",
+  "originHash" : "6e3fcf8724d6b7d2d0bbffc25b4ec3b9d8b65a6ef53d157498d5447fd26cf5db",
   "pins" : [
     {
       "identity" : "lcecryptokitbinary",

Package.swift

@@ -24,10 +24,10 @@ let targetDependencies: [Target.Dependency] = enableCryptoBinary
 let package = Package(
     name: "LCEssentials",
     platforms: [
-        .iOS(.v13),
+        .iOS(.v15),
         .macOS(.v10_15),
         .tvOS(.v13),
-        .watchOS(.v6)
+        .watchOS(.v8)
     ],
     products: [
         .library(

Sources/LCEssentials/Classes/LCEssentials+API+Upload.swift

@@ -30,7 +30,7 @@ public extension API {
     ///
     /// The body is serialised to a temporary file and streamed from disk, so a
     /// large file never becomes fully resident in memory. The temp file is
-    /// always removed before returning.
+    /// always removed before returning, on success and on throw.
     ///
     /// - Parameters:
     ///   - url: The URL string. `{name}` placeholders are filled from `pathParams`.
@@ -55,20 +55,9 @@ public extension API {
         timeoutInterval: TimeInterval = 120,
         networkServiceType: URLRequest.NetworkServiceType = .default
     ) async throws -> T {
-        let prepared = try buildUploadRequest(url: url, method: method, form: form,
-                                              pathParams: pathParams, headers: headers,
-                                              timeout: timeoutInterval, serviceType: networkServiceType)
-        defer { try? FileManager.default.removeItem(at: prepared.bodyFile) }
-
-        if debug { API.requestLOG(method: method, request: prepared.request) }
-        let (session, mustInvalidate) = makeSession()
-        defer { if mustInvalidate { session.finishTasksAndInvalidate() } }
-
-        let (data, response) = try await API.performUpload(prepared.request,
-                                                          fromFile: prepared.bodyFile,
-                                                          session: session)
-        return try API.finishUpload(data: data, response: response,
-                                    method: method, request: prepared.request, debug: debug)
+        try await runUpload(url: url, method: method, form: form, pathParams: pathParams,
+                            headers: headers, debug: debug, timeout: timeoutInterval,
+                            serviceType: networkServiceType, progressDelegate: nil)
     }
 
     /// Multipart upload that reports progress.
@@ -79,7 +68,6 @@ public extension API {
     ///
     /// - Parameter onProgress: invoked on an arbitrary queue; hop to the main
     ///   actor yourself before touching UI.
-    @available(iOS 15.0, *)
     func upload<T: Decodable & Sendable>(
         url: String,
         method: httpMethod = .post,
@@ -91,22 +79,12 @@ public extension API {
         networkServiceType: URLRequest.NetworkServiceType = .default,
         onProgress: @escaping @Sendable (Double) -> Void
     ) async throws -> T {
-        let prepared = try buildUploadRequest(url: url, method: method, form: form,
-                                              pathParams: pathParams, headers: headers,
-                                              timeout: timeoutInterval, serviceType: networkServiceType)
-        defer { try? FileManager.default.removeItem(at: prepared.bodyFile) }
-
-        if debug { API.requestLOG(method: method, request: prepared.request) }
-        let (session, mustInvalidate) = makeSession()
-        defer { if mustInvalidate { session.finishTasksAndInvalidate() } }
-
-        let progressDelegate = UploadProgressDelegate(onProgress: onProgress)
-        let (data, response) = try await session.upload(for: prepared.request,
-                                                        fromFile: prepared.bodyFile,
-                                                        delegate: progressDelegate)
+        let result: T = try await runUpload(url: url, method: method, form: form,
+                                            pathParams: pathParams, headers: headers, debug: debug,
+                                            timeout: timeoutInterval, serviceType: networkServiceType,
+                                            progressDelegate: UploadProgressDelegate(onProgress: onProgress))
         onProgress(1.0)
-        return try API.finishUpload(data: data, response: response,
-                                    method: method, request: prepared.request, debug: debug)
+        return result
     }
 }
 
@@ -115,6 +93,33 @@ public extension API {
 @available(iOS 13.0.0, *)
 extension API {
 
+    private func runUpload<T: Decodable & Sendable>(
+        url: String,
+        method: httpMethod,
+        form: MultipartForm,
+        pathParams: [String: String],
+        headers: [String: String],
+        debug: Bool,
+        timeout: TimeInterval,
+        serviceType: URLRequest.NetworkServiceType,
+        progressDelegate: UploadProgressDelegate?
+    ) async throws -> T {
+        let prepared = try buildUploadRequest(url: url, method: method, form: form,
+                                              pathParams: pathParams, headers: headers,
+                                              timeout: timeout, serviceType: serviceType)
+        defer { try? FileManager.default.removeItem(at: prepared.bodyFile) }
+
+        if debug { API.requestLOG(method: method, request: prepared.request) }
+        let (session, mustInvalidate) = makeSession()
+        defer { if mustInvalidate { session.finishTasksAndInvalidate() } }
+
+        let (data, response) = try await session.upload(for: prepared.request,
+                                                        fromFile: prepared.bodyFile,
+                                                        delegate: progressDelegate)
+        return try API.finishUpload(data: data, response: response,
+                                    method: method, request: prepared.request, debug: debug)
+    }
+
     private func buildUploadRequest(
         url: String,
         method: httpMethod,
@@ -147,30 +152,11 @@ extension API {
             throw friendlyError(code: code, data: data)
         }
     }
-
-    /// Bridges `URLSession.uploadTask(with:fromFile:)` to `async` so the base
-    /// `upload` works down to iOS 13 (`URLSession.upload(for:fromFile:)` is iOS 15+).
-    fileprivate static func performUpload(_ request: URLRequest,
-                                          fromFile fileURL: URL,
-                                          session: URLSession) async throws -> (Data, URLResponse) {
-        try await withCheckedThrowingContinuation { continuation in
-            let task = session.uploadTask(with: request, fromFile: fileURL) { data, response, error in
-                if let error {
-                    continuation.resume(throwing: error)
-                } else if let data, let response {
-                    continuation.resume(returning: (data, response))
-                } else {
-                    continuation.resume(throwing: API.defaultError)
-                }
-            }
-            task.resume()
-        }
-    }
 }
 
 /// Forwards `URLSession` upload progress to a `@Sendable` closure. Immutable
 /// after `init`, safe to hand to `URLSession` as a task delegate.
-@available(iOS 15.0, *)
+@available(iOS 13.0.0, *)
 private final class UploadProgressDelegate: NSObject, URLSessionTaskDelegate, @unchecked Sendable {
 
     private let onProgress: @Sendable (Double) -> Void

Tests/LCEssentialsTests/APIUploadTests.swift

@@ -87,7 +87,6 @@ final class APIUploadTests: XCTestCase {
         XCTAssertEqual(tempCountInDir(dir), before)
     }
 
-    @available(iOS 15.0, *)
     func testProgressOverloadDeliversFinalCompletionAndDecodes() async throws {
         StubURLProtocol.setStub(.init(statusCode: 200, body: Data(#"{"ok":true}"#.utf8)))