SwiftReload

This is an experimental project that enables hot reloading of Swift code in SwiftPM based projects.

Platforms

Platform	CI Status	Support Status
macOS		✅
Linux		✅
Windows		🚧

Quick Start

Add SwiftReload to your project's dependencies in Package.swift:

dependencies: [
    .package(url: "https://github.com/ShaftUI/SwiftReload.git", branch: "main")
]

Add SwiftReload to your target's dependencies:

.executableTarget(
    name: "MyApp",
    dependencies: [
        "SwiftReload"
    ]
)

Add -enable-private-imports and -enable-implicit-dynamic flag to your target's build settings:

.executableTarget(
    name: "MyApp",
    dependencies: [
        "SwiftReload"
    ],
    swiftSettings: [
        .unsafeFlags(
            ["-Xfrontend", "-enable-private-imports"],
            .when(configuration: .debug)
        ),
        .unsafeFlags(
            ["-Xfrontend", "-enable-implicit-dynamic"],
            .when(configuration: .debug)
        ),
    ],
    linkerSettings: [
        .unsafeFlags(
            ["-Xlinker", "--export-dynamic"],
            .when(platforms: [.linux, .android], configuration: .debug)
        ),
    ]
)

This enables method swizzling, which SwiftReload uses to replace code at runtime.

On Linux, you also need to add the -Xlinker --export-dynamic flag to the linker settings to export all symbols from the executable.

Add the following code at the beginning of your main.swift:

import SwiftReload

LocalSwiftReloader().start()

For complete example, see the Sources/SwiftReloadExample directory.

With ShaftUI

The LocalSwiftReloader has a onReload callback that is called when the code reload is triggered. You can call backend.scheduleReassemble in the callback to rebuild the UI.

#if DEBUG
    import SwiftReload
    LocalSwiftReloader(onReload: backend.scheduleReassemble).start()
#endif

How it works

SwiftReload monitors changes to the source files of your project. When a change is detected, it recompiles the updated source files to a dynamic library and loads it into the running process. The dynamic library then replaces the existing code in the process, effectively enabling hot reloading of Swift code.