AppConfig

A Swift package which makes it easy to have a set of app-wide properties which can be persisted and loaded to/from the filesystem (encoded as JSON).

Useful for applications on Linux, where (at the time of writing) Foundation's UserDefaults don't work. I assume that this will be rectified in The new Swift-based Foundation Project

If you are targetting Apple's platforms, then you should probably use Foundation's UserDefaults class instead of this package. Hacking With Swift Example for using UserDefaults

---

Note

As this repo is public, I should probably learn how to do tests…

---

Adding AppConfig as a dependency to your package

You need to declare your dependency in your Package.swift manifest file in the dependencies array:

.package(url: "https://github.com/Diggory/AppConfig.git", from: "0.0.1"),

And also to your application/library target, add "AppConfig" to your dependencies, e.g. like this:

.target(name: "YourAppNameHere", dependencies: [
    .product(name: "AppConfig", package: "AppConfig")
],

e.g. in a full package manifest

// swift-tools-version: 5.7
import PackageDescription

let package = Package(
	name: "YourPackageNameHere",
	dependencies: [
		.package(url: "https://github.com/Diggory/AppConfig.git", from: "0.0.1"),
	],
	targets: [
		.executableTarget(
			name: "YourExecutableNameHere",
			dependencies: [
				.product(name: "AppConfig", package: "AppConfig")
			]),
	]
)

---

Examples

Setup

// Import AppConfig to use it.
import AppConfig

//	The appConfig needs to know what your app name is, 
//	so that it can store the config in the correctly named files.
var appConfig = AppConfig(configFileName: "YourAppNameHere")

//	In which folder should the config files be saved?  
//	/etc is only available to root.  
//	/tmp can be purged at any time (but can work for our examples).
appConfig.configDirectoryString = "/tmp/"

1) An example where an existing working config file exists /etc/YourAppName.json or a default config file exists /etc/YourAppName_defaults.json

//	Attempt to load the config from disc
if (!appConfig.loadConfigFromFilesystem()) {
	print("Unable to load app config from filesystem (neither from active config file, nor the defaults config file…)")
}

---

2) An example where neither an existing config file exists nor a default config file exists. In this case we make defaults in code. Useful in the failure case above.

if (!appConfig.setInitialConfigWhereNoDefaultsInFilesystem(initialProps: ["Bing": "Bong"])) {
		print("Cannot set initial config - there appears to be an existing config in the filesytem.  Either a user generated one, or a default file....")
}

A combination of 1 and 2:

//	Attempt to load the config from disc
if (!appConfig.loadConfigFromFilesystem()) {
	print("Unable to load app config from filesystem (neither from active config file, nor the defaults config file…)")
	print("Setting config from a hard-coded property")
	if (!appConfig.setInitialConfigWhereNoDefaultsInFilesystem(initialProps: ["Bing": "Bong"])) {
		//	Technically this case should never happen in this specific closure as we have already checked for this case in loadConfigFromFilesystem()…
		print("Cannot set initial config - there appears to be an existing config in the filesytem.  Either a user generated one, or a default file....")
	}
}

Setting a property to the store

let key = "bing"
appConfig[key] = "bang!"

Getting a property from the store

let key = "bing"
let retrievedConfigProperty = appConfig[key]
print("\(key): \(retrievedConfigProperty ?? "No config property for key: \(key)")")

result:

bing: bang!