Update docs on local builds

Author: simolus3

Package.swift

@@ -4,6 +4,35 @@
 import PackageDescription
 let packageName = "PowerSync"
 
+// Set this to the absolute path of your Kotlin SDK checkout if you want to use a local Kotlin
+// build. Also see docs/LocalBuild.md for details
+let localKotlinSdkOverride: String? = nil
+
+// Our target and dependency setup is different when a local Kotlin SDK is used. Without the local
+// SDK, we have no package dependency on Kotlin and download the XCFramework from Kotlin releases as
+// a binary target.
+// With a local SDK, we point to a `Package.swift` within the Kotlin SDK containing a target pointing
+// towards a local framework build
+var conditionalDependencies: [Package.Dependency] = []
+var conditionalTargets: [Target] = []
+var kotlinTargetDependency = Target.Dependency.target(name: "PowerSyncKotlin")
+
+if let kotlinSdkPath = localKotlinSdkOverride {
+    // We can't depend on local XCFrameworks outside of this project's root, so there's a Package.swift
+    // in the PowerSyncKotlin project pointing towards a local build.
+    conditionalDependencies.append(.package(path: "\(kotlinSdkPath)/PowerSyncKotlin"))
+
+    kotlinTargetDependency = .product(name: "PowerSyncKotlin", package: "PowerSyncKotlin")
+} else {
+    // Not using a local build, so download from releases
+    conditionalTargets.append(.binaryTarget(
+        name: "PowerSyncKotlin",
+        // TODO: Use GitHub release once https://github.com/powersync-ja/powersync-kotlin/releases/tag/untagged-fde4386dec502ec27067 is published
+        url: "https://fsn1.your-objectstorage.com/simon-public/powersync.zip",
+        checksum: "b6770dc22ae31315adc599e653fea99614226312fe861dbd8764e922a5a83b09"
+    ))
+}
+
 let package = Package(
     name: packageName,
     platforms: [
@@ -18,31 +47,19 @@ let package = Package(
     ],
     dependencies: [
         .package(url: "https://github.com/powersync-ja/powersync-sqlite-core-swift.git", "0.3.14"..<"0.4.0")
-    ],
+    ] + conditionalDependencies,
     targets: [
         // Targets are the basic building blocks of a package, defining a module or a test suite.
         // Targets can depend on other targets in this package and products from dependencies.
         .target(
             name: packageName,
             dependencies: [
-                .target(name: "PowerSyncKotlin"),
+                kotlinTargetDependency,
                 .product(name: "PowerSyncSQLiteCore", package: "powersync-sqlite-core-swift")
             ]),
         .testTarget(
             name: "PowerSyncTests",
             dependencies: ["PowerSync"]
         ),
-        // If you want to use a local build, comment out this reference and update the other.
-        // See docs/LocalBuild.md
-        .binaryTarget(
-            name: "PowerSyncKotlin",
-            // TODO: Use GitHub release once https://github.com/powersync-ja/powersync-kotlin/releases/tag/untagged-fde4386dec502ec27067 is published
-            url: "https://fsn1.your-objectstorage.com/simon-public/powersync.zip",
-            checksum: "b6770dc22ae31315adc599e653fea99614226312fe861dbd8764e922a5a83b09"
-        ),
-        // .binaryTarget(
-        //     name: "PowerSyncKotlin",
-        //     path: "/path/to/powersync-kotlin/PowerSyncKotlin/build/XCFrameworks/debug/PowerSyncKotlin.xcframework"
-        // )
-    ]
+    ] + conditionalTargets
 )

docs/LocalBuild.md

@@ -10,14 +10,12 @@ To do this, first create an XCFramework from your Kotlin checkout:
 ./gradlew PowerSyncKotlin:assemblePowerSyncKotlinDebugXCFramework
 ```
 
-Then, point the `binaryTarget` dependency in `Package.swift` towards the path of your generated
-XCFramework:
+Next, you need to update the `Package.swift` to, instead of downloading a
+prebuilt XCFramework archive from a Kotlin release, use your local build.
+For this, set the `localKotlinSdkOverride` variable to your path:
 
 ```Swift
-.binaryTarget(
-    name: "PowerSyncKotlin",
-    path: "/path/to/powersync-kotlin/PowerSyncKotlin/build/XCFrameworks/debug/PowerSyncKotlin.xcframework"
-)
+let localKotlinSdkOverride: String? = "/path/to/powersync-kotlin/"
 ```
 
 Subsequent Kotlin changes should get picked up after re-assembling the Kotlin XCFramework.