Drop Swift 5 (#969)

Swift 5 is dead for 1y now:
https://developer.apple.com/news/upcoming-requirements/?id=02212025a

Notable changes:
- consolidates `Package.swift`, `6.2` will be removed as we move to
`.26`
- removes all conditionals (mostly around concurrency)
- leaves macOS 14 CI for now, with updated Xcode

This is a prerequisite to:
#922

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: pblazej

.changes/drop-swift-5-support

@@ -0,0 +1 @@
+minor type="changed" "Drop Xcode 15 (Swift 5.x) support; minimum is now Xcode 16 / Swift 6.0"

.github/workflows/ci.yaml

@@ -27,19 +27,19 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          # https://github.com/actions/runner-images/blob/main/images/macos/macos-14-Readme.md
+          # https://github.com/actions/runner-images/blob/main/images/macos/macos-14-arm64-Readme.md
           - os: macos-14
-            xcode: 15.4
-            platform: "iOS Simulator,name=iPhone 15 Pro,OS=17.5"
+            xcode: 16.2
+            platform: "iOS Simulator,name=iPhone 16 Pro,OS=18.2"
           - os: macos-14
-            xcode: 15.4
+            xcode: 16.2
             platform: "macOS"
           - os: macos-14
-            xcode: 15.4
+            xcode: 16.2
             platform: "macOS,variant=Mac Catalyst"
           - os: macos-14
-            xcode: 15.4
-            platform: "tvOS Simulator,name=Apple TV,OS=17.5"
+            xcode: 16.2
+            platform: "tvOS Simulator,name=Apple TV,OS=18.2"
 
           # https://github.com/actions/runner-images/blob/main/images/macos/macos-15-Readme.md
           - os: macos-15

.github/workflows/cocoapods-lint.yaml

@@ -15,7 +15,7 @@ jobs:
       matrix:
         include:
           - os: macos-14
-            xcode: 15.4
+            xcode: 16.2
           - os: macos-15
             xcode: 16.4
           - os: macos-26

.swift-version

@@ -1,3 +1,4 @@
+--swiftversion 6.0
 --exclude Sources/LiveKit/Protos
 --header "/*\n * Copyright {year} LiveKit\n *\n * Licensed under the Apache License, Version 2.0 (the \"License\");\n * you may not use this file except in compliance with the License.\n * You may obtain a copy of the License at\n *\n *     http://www.apache.org/licenses/LICENSE-2.0\n *\n * Unless required by applicable law or agreed to in writing, software\n * distributed under the License is distributed on an \"AS IS\" BASIS,\n * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n * See the License for the specific language governing permissions and\n * limitations under the License.\n */"
 --ifdef no-indent

.swiftformat

@@ -83,17 +83,17 @@ Threading:
 
 ### Language Version
 
-- Supported Xcode versions: current minus two major versions (including beta)
-- `Package.swift` and `.swift-version` declare the **oldest** supported version (e.g., `swift-tools-version:5.9`) for backwards compatibility
-- Keep all manifests in sync when adding dependencies
+- Minimum supported Xcode is Xcode 16 (Swift 6.0); see Apple's [App Store submission requirements](https://developer.apple.com/news/upcoming-requirements/?id=02212025a)
+- `Package.swift` (`swift-tools-version:6.0`) declares the **oldest** supported version
+- Keep `Package.swift`, `LiveKitClient.podspec`, and `.swiftformat`'s `--swiftversion` in sync when changing the minimum
 - New code should use the latest stable Swift version
-- Some constructs require `#if swift` or `#if compiler` directives for version compatibility:
+- Some constructs require `#if swift` or `#if compiler` directives to support newer-than-minimum toolchains:
 
 ```swift
-#if swift(>=6.0)
-public nonisolated(unsafe) static let shared = AudioManager()
+#if swift(>=6.2)
+private static let playAndRecordOptions: AVAudioSession.CategoryOptions = [.mixWithOthers, .allowBluetoothHFP, .allowBluetoothA2DP, .allowAirPlay]
 #else
-public static let shared = AudioManager()
+private static let playAndRecordOptions: AVAudioSession.CategoryOptions = [.mixWithOthers, .allowBluetooth, .allowBluetoothA2DP, .allowAirPlay]
 #endif
 ```
 

AGENTS.md

@@ -19,12 +19,4 @@ Pod::Spec.new do |spec|
   spec.dependency("SwiftProtobuf")
 
   spec.resource_bundles = {"Privacy" => ["Sources/LiveKit/PrivacyInfo.xcprivacy"]}
-
-  xcode_output = `xcodebuild -version`.strip
-  major_version = xcode_output =~ /Xcode\s+(\d+)/ ? $1.to_i : 15
-
-  spec.pod_target_xcconfig = {
-    "OTHER_SWIFT_FLAGS" => major_version >=15  ?
-      "-enable-experimental-feature AccessLevelOnImport" : ""
-  }
 end

LiveKitClient.podspec

@@ -1,5 +1,5 @@
-// swift-tools-version:5.9
-// (Xcode15.0+)
+// swift-tools-version:6.0
+// (Xcode16.0+)
 
 import PackageDescription
 
@@ -43,9 +43,6 @@ let package = Package(
             ],
             resources: [
                 .process("PrivacyInfo.xcprivacy"),
-            ],
-            swiftSettings: [
-                .enableExperimentalFeature("AccessLevelOnImport"),
             ]
         ),
         .target(
@@ -77,7 +74,5 @@ let package = Package(
             ]
         ),
     ],
-    swiftLanguageVersions: [
-        .v5,
-    ]
+    swiftLanguageModes: [.v5, .v6]
 )

Package.swift

@@ -44,9 +44,6 @@ let package = Package(
             ],
             resources: [
                 .process("PrivacyInfo.xcprivacy"),
-            ],
-            swiftSettings: [
-                .enableExperimentalFeature("AccessLevelOnImport"),
             ]
         ),
         .target(
@@ -78,8 +75,5 @@ let package = Package(
             ]
         ),
     ],
-    swiftLanguageModes: [
-        .v5, // opt-out from dynamic actor isolation checks
-        .v6,
-    ]
+    swiftLanguageModes: [.v5, .v6]
 )