Add xcode26_3 project format (objectVersion 100) (#1648)

* Add xcode26_3 project format (objectVersion 100)

Adds a `xcode26_3` case to `ProjectFormat`, selectable via the
`projectFormat` spec option, which generates projects in the Xcode 26.3
format: `objectVersion = 100` and `preferredProjectObjectVersion = 100`,
with no `compatibilityVersion` (matching the existing Xcode 16.x formats).
The default format is unchanged.

Resolves #1620

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Add PR number to CHANGELOG entry

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

Author: Raymondriter

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Added
 - Added `buildArchitectures` to scheme build options and target schemes, to control Xcode's "Override Architectures" scheme setting #1642 @arhxam
 - Added FAQ documentation on how to add an Xcode capability, such as In-App Purchase #1644 @Hokila
+- Added `xcode26_3` `projectFormat` option for the Xcode 26.3 project format (`objectVersion = 100`) #1648 @Raymondriter
 
 ### Changed
 - Generated schemes now default to `buildArchitectures: matchRunDestination` ("Match Run Destination"), matching Xcode's default for new schemes. Previously schemes used each target's architecture settings. Set `buildArchitectures: useTargetSettings` to keep the previous behaviour #1642 @yonaskolb

Docs/ProjectSpec.md

@@ -134,6 +134,7 @@ Note that target names can also be changed by adding a `name` property to a targ
 - [ ] **tabWidth**: **Int** - If this is specified, the Xcode project will override the user's setting for indent width in number of spaces.
 - [ ] **xcodeVersion**: **String** - The version of Xcode. This defaults to the latest version periodically. You can specify it in the format `0910` or `9.1`
 - [ ] **projectFormat**: **String** - The version of Xcode project. By default this is set to `xcode16_0`
+  - `xcode26_3`: Xcode 26.3
   - `xcode16_3`: Xcode 16.3
   - `xcode16_0`: Xcode 16.0
   - `xcode15_3`: Xcode 15.3

Sources/XcodeGenKit/ProjectFormat.swift

@@ -3,6 +3,7 @@ public extension ProjectFormat {
 }
 
 public enum ProjectFormat: String {
+    case xcode26_3
     case xcode16_3
     case xcode16_0
     case xcode15_3
@@ -11,6 +12,7 @@ public enum ProjectFormat: String {
 
     public var objectVersion: UInt {
         switch self {
+        case .xcode26_3: 100
         case .xcode16_3: 90
         case .xcode16_0: 77
         case .xcode15_3: 63
@@ -21,14 +23,14 @@ public enum ProjectFormat: String {
 
     public var preferredProjectObjectVersion: UInt? {
         switch self {
-        case .xcode16_3, .xcode16_0: objectVersion
+        case .xcode26_3, .xcode16_3, .xcode16_0: objectVersion
         case .xcode15_3, .xcode15_0, .xcode14_0: nil
         }
     }
 
     public var compatibilityVersion: String? {
         switch self {
-        case .xcode16_3, .xcode16_0: nil
+        case .xcode26_3, .xcode16_3, .xcode16_0: nil
         case .xcode15_3: "Xcode 15.3"
         case .xcode15_0: "Xcode 15.0"
         case .xcode14_0: "Xcode 14.0"

Tests/XcodeGenKitTests/PBXProjGeneratorTests.swift

@@ -507,6 +507,30 @@ class PBXProjGeneratorTests: XCTestCase {
         }
     }
 
+    func testDefaultProjectFormat() throws {
+        let project = Project(name: "Test")
+
+        let pbxProj = try PBXProjGenerator(project: project).generate()
+        let pbxProject = try XCTUnwrap(pbxProj.rootObject)
+
+        XCTAssertEqual(project.projectFormat, .xcode16_0)
+        XCTAssertEqual(pbxProj.objectVersion, 77)
+        XCTAssertEqual(pbxProject.preferredProjectObjectVersion, 77)
+        XCTAssertNil(pbxProject.compatibilityVersion)
+    }
+
+    func testXcode26_3ProjectFormat() throws {
+        let project = Project(name: "Test", options: SpecOptions(projectFormat: "xcode26_3"))
+
+        let pbxProj = try PBXProjGenerator(project: project).generate()
+        let pbxProject = try XCTUnwrap(pbxProj.rootObject)
+
+        XCTAssertEqual(project.projectFormat, .xcode26_3)
+        XCTAssertEqual(pbxProj.objectVersion, 100)
+        XCTAssertEqual(pbxProject.preferredProjectObjectVersion, 100)
+        XCTAssertNil(pbxProject.compatibilityVersion)
+    }
+
     func testProductsGroupIsSet() throws {
         let target = Target(name: "TestApp", type: .application, platform: .iOS)
         let project = Project(name: "Test", targets: [target])