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johnno1962/HotReloading v4.2.6
Hot reloading as a Swift Package
⭐️ 282
🕓 2 weeks ago
iOS macOS tvOS
.package(url: "https://github.com/johnno1962/HotReloading.git", from: "v4.2.6")

Yes, HotReloading for Swift, Objective-C & C++!

This project is the InjectionIII app for live code updates available as a Swift Package. i.e.:


Then, you can inject function implementations without having to rebuild your app... Icon

To try out an example project that is already set-up, clone this fork of SwiftUI-Kit.

To use on your project, simply add this repo as a Swift Package, add the following -Xlinker -interposable to Debug "Other Linker Flags", and then rebuild. You no longer need to add a "Run Script" build phase unless you want to inject on a device, in which case add the following to start the Injection daemon.

if [ -d $SYMROOT/../../SourcePackages ]; then

If you encounter undefined FSEventStream* symbols, this is due to using a macOS api in the simulator and you should find this goes away if add the following additional "Other Linker Flags": -Xlinker -undefined -Xlinker dynamic_lookup.

Remember not to release your app with this package configured.

You should see a message that the app has connected and which directories it is watching for source file changes. You can change these by using comma separated list in the environment variable INJECTION_DIRECTORIES. It you run the daemon it presents an icon on the menu bar you can use to access features such as tracing and remote control. The daemon also patches your project slightly to add the required "-Xlinker -interposable" "Other Linker Flags" for injecting the methods of structs so you may have to run the project a second time after adding the HotReloading package. If you choose to run the daemon when using the simulator, add the environment variable INJECTION_DAEMON to your scheme to have your app connect.

Consult the README of the InjectionIII project for more information in particular how to use it to inject SwiftUI using the HotSwiftUI protocol extension. It's the same code but you no longer need to download or run the app and the project is selected automatically.

Device Injection

This version of the HotReloading project and it's dependencies now support injection on a real iOS or tvOS device. It's early days and this version should still be considered beta software. The binary framework from the InjectionScratch repo that makes this possible is time limited for now to expire on September 15th 2022 until I find a more sustainable licensing solution should people find it useful. If your device doesn't connect, clone this project and configure your mac's WiFi IP address into the hostname variable in Package.swift. Then drag the clone onto your project to have it take the place of the configured Swift Package.

As Swift plays its cards pretty close to its chest it's not quite possible to initialise type meta data entirely correctly so your milage may vary more than using HotReloading in the simulator. In particular, if injected code crashes, the debugger will not display the line number but an address under the symbol "injected_code" instead. If you get stuck, use an @_exported import HotReloading in a source file and you should be able to type p HotReloading.stack to get a stack trace.

Also note that, as the HotReloading package needs to connect a network socket to your Mac to receive commands and new versions of code, expect a message the first time you run your app after adding the package asking you to "Trust" that your app should be allowed to do this. Likewise, at the Mac end (as the HotReloading daemon needs to open a network port to accept this connection) you may be prompted for permission if you have the macOS firewall turned on.

For SwifuUI you can force screen updates by following the conventions outlined in the HotSwiftUI project then you can experience something like "Xcode Previews", except for a fully functional app on an actual device!

Vapor injection

To use injection with Vapor web server, add this Swift package as a dependency to its Package.swift and as dependency of the "App" target then run vapour from inside Xcode. It will ask you to run a script to start the associated daemon processes which watches for source file changes from inside project directory. It's not possible to inject closures that have already been registered with routes however but if you delegate their implementation to the method of a class it can be injected. If you want to delegate to a top level function or the method of a struct you'll need to add the following to the executable target to enable "interposing":

    , linkerSettings: [
        .unsafeFlags(["-Xlinker", "-interposable"])]

Thanks to...

The App Tracing functionality uses the OliverLetterer/imp_implementationForwardingToSelector trampoline implementation via the SwiftTrace project under an MIT license.

SwiftTrace uses the very handy https://github.com/facebook/fishhook as an alternative to the dyld_dynamic_interpose dynamic loader private api. See the project source and header file included in the framework for licensing details.

The "Remote" server in this project which allows you to capture videos from your device includes code adapted from acj/TimeLapseBuilder-Swift

This release includes a very slightly modified version of the excellent canviz library to render "dot" files in an HTML canvas which is subject to an MIT license. The changes are to pass through the ID of the node to the node label tag (line 212), to reverse the rendering of nodes and the lines linking them (line 406) and to store edge paths so they can be coloured (line 66 and 303) in "canviz-0.1/canviz.js".

It also includes CodeMirror JavaScript editor for the code to be evaluated in the Xprobe browser under an MIT license.

$Date: 2022/04/05 $


Stars: 282
Last commit: 1 week ago
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